omap2430sdp_mmc_fix

The PRCM (0x490022E8)register was overwritten by the MMC code
which made the other peripherals like USB etc to stop working.
The following patch fixes the modification of PRCM register by
the MMC code. This patch is tested here on the OMAP2430 SDP board.

Signed-off-by: Arun K S <arunks@mistralsolutions.com>
Ack-by: Madhusudhan Chikkature Rajashekar" <madhu.cr@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>