iommu: msm: drop usage of arch specific cache line size

cache_line_size() may not be a static number for every
architecture but dynamically calculated size. Instead
use higher alignment of PAGE_SIZE for temporary
allocations.

Change-Id: Ib8a730a7f5eca650a5a98f20532ffeaa3b647491
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>