msm: kgsl: Set alignment to 0 when low on mapped memory

If CPU map returns error due to low memory then we need to set
the alignment to 0 and instead of setting it to PAGE_OFFSET. This
is because we then simply search of a free memory gap at page
boundary and disrerard alignment requirement since memory is
low.

Change-Id: I828f5d0120d6d530e0e8857bcd96c9d5f266da10
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>