ARM: OMAP: plat-omap changes for 2430 SDP

This patch adds minimal OMAP2430 support to plat-omap files to
get the kernel booting on 2430SDP.

Signed-off-by: Syed Mohammed Khasim <x0khasim@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>