msm_fb: Clean up of frame buffer 4KB alignment changes

Remove redundant code from the 4 KB alignment patch
and reduce the overhead of calculation of the hole
size by using bitwise operators in its calculation.

Change-Id: I1706484249bf8e01b250e91fa87e00f6021d9a72
CRs-fixed: 325134
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>
Signed-off-by: garwedgess <garethwilliams21@gmail.com>