usb: otg: OMAP4430: Save/restore the context

Add the context save/restore for the control module register
used for OMAP4430 musb with UTMI embedded PHY interface.

Signed-off-by: Hema HK <hemahk@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>