gralloc: Remove PAGE_SIZE 4096 usage

Android V will support page size agnostic targets. The bionic macro
PAGE_SIZE won't be defined for the agnostic targets. The PAGE_SIZE
macro will be replaced by getpagesize(), which provide the real
page size, in gralloc.

Bug: 296578499
Test: source build/envsetup.sh
      lunch aosp_cf_arm64_phone_pgagnostic
Change-Id: I963468712a7d65160201b720de0efe009921ad53
1 file changed