msm: kgsl: Restrict the maximum memory entries for bulk cache sync

Restrict the maximum number of memory entries that can be specified
to a single bulk cache sync call to PAGE_SIZE / sizeof(unsigned int)
so that the allocation can always fit within one page.

CRs-fixed: 578062
Change-Id: Ic0dedbad07e1986cd6ccc5b260ffef82b5adb6d3
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>