ion: msm_ion: Add freeze_late and restore_early callbacks

Delay the freeze callback of ion driver to allow
other clients to free their secure memory allocations.
In the restore path, the ion must be initialized
early before other clients make their allocations.

Change-Id: Iba0b8a0a1b4c26247d704a62c4b6f0675e93f7a2
Signed-off-by: Shreyas K K <shrekk@codeaurora.org>