omap2: Add OHCI USB platform init for 2430 SDP

Add platform init code for OHCI USB on OMAP2430 SDP

Signed-off-by: Viral Mehta <viral.mehta@lntinfotech.com>
[tony@atomide.com: Updated subject to mention the board name]
Signed-off-by: Tony Lindgren <tony@atomide.com>