ARM: OMAP: Remove useless omap_sram_error function.

This patch removes fixes omap_sram_error() function and replace the
error paths with BUG_ON.

The proposed fix was suggested by Russell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>