ARM: OMAP4+: Initialize SAR RAM base early for proper CPU1 reset for kexec

Prepare things for making kexec work on SMP omap variants by initializing
SARM RAM base early. This allows us to configure CPU1 for kexec in case
the previous kernel has put CPU1 in low power mode.

Note that this should not prevent moving other SAR RAM code to live
under drivers. However for kexec, we will need this very early.

Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Tested-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>