gpu: ion: Don't flush allocatoins that come from the page pools

Change-Id: I7942a374a3240f683e52560386232f52d9ea4b5c
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
Git-commit: 210d4774f4d4b58cca042d32ea21e1bac784f273
Git-repo: https://android.googlesource.com/kernel/common


[lauraa@codeaurora.org: Change sync API to match what the later
kernel need]
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>