ARM: OMAP4+: Use common scratchpad SAR RAM offsets for all architectures

Choose the common scratch pad offsets, so that same offsets can work for
OMAP4 and OMAP5 devices. It simplifies code and also allows the re-use as
is on OMAP5 devices. Note that these offsets are used by low power
code for various power state management. They are not hardware register
offsets.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>