ARM: OMAP: sram: skip the first 16K on OMAP3 HS

In some OMAP3 HS devices (at least Nokia N9 and N950), the public SRAM
seems to conflict with secure portition of SRAM. When booting the 3.6-rc3
kernel (and also earlier) on these devices, the kernel gets tainted with
tons of the following warnings:

	[    6.894348] In-band Error seen by MPU  at address 0
	[...]
	[    6.894378] WARNING: at arch/arm/mach-omap2/omap_l3_smx.c:162

Fix this by skipping the first 16K of the public SRAM. (Note that the
mapping could not be changed, as it resulted in secure monitor call
failure in save_secure_sram().)

This will leave 12K SRAM available that should be still sufficient. The
patch has been boot tested with vanilla 3.6-rc3 on N900, N950 and N9.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>