ARM: 6408/1: omap: Map only available sram memory

Currently we map 1 MB section while setting up SRAM on OMAPs
Regardless of the actual memory. The physical OCM RAM available
on OMAP SOCs is in order of KBs. This patch maps only available
sram and cleans up some un-necessary cpu_is_xxx checks.

Mapping un-available or non-accessible(secure) memory on the newer ARM
processor is dangerous. Because ARM CPUs can now speculatively prefetch,
we should avoid mapping any no-existing or secure memory.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>