gpu: ion: Add ION support for fmem

FMEM allows ION to release memory for other
purposes when ION clients are not using the
memory.

Add new heap type for fmem that make calls
into fmem API to transition memory from T to
C state and vice versa. Add support for
fmem to content protection heap.

Change-Id: I95f949b57c99949e6eafe6a6f5fd147bdaa264f6
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>