msm: iomap: Add static iomap for PS hold register on 8910.

Allow reset via PS hold toggle.
Static mapping is required to enable reset at any early stage
of boot up process due to panic.

Change-Id: I083b041d778c3311aab3b95c6c32a03f7ca22e5a
Signed-off-by: Hanumant Singh <hanumant@codeaurora.org>