ARM: OMAP2+: Add clock domain support for dm816x

ARM: OMAP2+: Add clock domain support for dm816x

This patch adds required definitions and structures for clockdomain
initialization, so omap3xxx_clockdomains_init() was substituted by
new ti81xx_clockdomains_init() while early initialization of
TI81XX platform.

Note that we now need to have 81xx in a separate CONFIG_SOC_TI81XX
block instead inside the ifdef block for omap3 to avoid make
randconfig build errors.

This code is based on the TI81XX-LINUX-PSP-04.04.00.02 patches
published at:

http://downloads.ti.com/dsps/dsps_public_sw/psp/LinuxPSP/TI81XX_04_04/04_04_00_02/index_FDS.html

Cc: Brian Hutchinson <b.hutchman@gmail.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Aida Mynzhasova <aida.mynzhasova@skitlab.ru>
[tony@atomide.com: updated to apply, renamed to clockdomains81xx.c,
 fixed to use am33xx_clkdm_operations, various fixes suggested by
 Paul Walmsley]
Reviewed-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>