[media] cx25821: get rid of warning: no previous prototype

[media] cx25821: get rid of warning: no previous prototype

drivers/media/pci/cx25821/cx25821-audio-upstream.c:136:5: warning: no previous prototype for 'cx25821_risc_buffer_upstream_audio' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-audio-upstream.c:200:6: warning: no previous prototype for 'cx25821_free_memory_audio' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-audio-upstream.c:259:5: warning: no previous prototype for 'cx25821_get_audio_data' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-audio-upstream.c:354:5: warning: no previous prototype for 'cx25821_openfile_audio' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-audio-upstream.c:47:5: warning: no previous prototype for 'cx25821_sram_channel_setup_upstream_audio' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-audio-upstream.c:493:5: warning: no previous prototype for 'cx25821_audio_upstream_irq' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-audio-upstream.c:637:5: warning: no previous prototype for 'cx25821_start_audio_dma_upstream' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-biffuncs.h:28:11: warning: no previous prototype for 'getBit' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-biffuncs.h:33:12: warning: no previous prototype for 'clearBitAtPos' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-biffuncs.h:38:12: warning: no previous prototype for 'setBitAtPos' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-i2c.c:332:6: warning: no previous prototype for 'cx25821_av_clk' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video.c:294:5: warning: no previous prototype for 'cx25821_restart_video_queue' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video.c:345:6: warning: no previous prototype for 'cx25821_vid_timeout' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:176:5: warning: no previous prototype for 'cx25821_risc_buffer_upstream' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:303:5: warning: no previous prototype for 'cx25821_get_frame' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:408:5: warning: no previous prototype for 'cx25821_openfile' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:489:5: warning: no previous prototype for 'cx25821_upstream_buffer_prepare' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:551:5: warning: no previous prototype for 'cx25821_video_upstream_irq' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:667:6: warning: no previous prototype for 'cx25821_set_pixelengine' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream.c:699:5: warning: no previous prototype for 'cx25821_start_video_dma_upstream' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream-ch2.c:126:5: warning: no previous prototype for 'cx25821_risc_buffer_upstream_ch2' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream-ch2.c:258:5: warning: no previous prototype for 'cx25821_get_frame_ch2' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream-ch2.c:363:5: warning: no previous prototype for 'cx25821_openfile_ch2' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream-ch2.c:510:5: warning: no previous prototype for 'cx25821_video_upstream_irq_ch2' [-Wmissing-prototypes]
drivers/media/pci/cx25821/cx25821-video-upstream-ch2.c:650:5: warning: no previous prototype for 'cx25821_start_video_dma_upstream_ch2' [-Wmissing-prototypes]

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>