ARM: OMAP: am33xx: Update common omap platform files

This patch updates the common platform files with AM335X device
support (AM33XX family).

The approach taken in this patch is,
AM33XX device will be considered as OMAP3 variant, and a separate
SoC class created for AM33XX family of devices with a subclass type
for AM335X device, which is newly added device in the family.

This means, cpu_is_omap34xx(), cpu_is_am33xx() and cpu_is_am335x()
checks will return success on AM335X device.
A kernel config option CONFIG_SOC_OMAPAM33XX is added under OMAP3
to include support for AM33XX build.

Also, cpu_mask and RATE_IN_XXX flags have crossed 8 bit hence
struct clksel_rate.flags, struct prcm_config.flags and cpu_mask
are changed to u16 from u8.

Signed-off-by: Afzal Mohammed <afzal@ti.com>
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Cc: Hemant Pedanekar <hemantp@ti.com>
[tony@atomide.com: left out CK_AM33XX for now]
Signed-off-by: Tony Lindgren <tony@atomide.com>