staging: android: Split uapi out of ashmem.h

staging: android: Split uapi out of ashmem.h

Move the userspace interface of ashmem.h to
drivers/staging/android/uapi/ashmem.h

Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Colin Cross <ccross@android.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Colin Cross <ccross@android.com>
[jstultz: Minor commit message tweak]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>