OMAP4: PRCM: Add SCRM header file

Add the header file with scrm registers absolute address, offset
and bitfields.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
[paul@pwsan.com: renamed OMAP4_SCRM to OMAP4_SCRM_BASE]
Signed-off-by: Paul Walmsley <paul@pwsan.com>