gpu: ion: Add ION Memory Manager

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
Signed-off-by: Ronny Schmatzler <schmatzler@googlemail.com>
gpu: ion: Several fixes

Fix some cases where locks were not released on error paths
Change heap->prio to heap->id to make meaning clearer
Fix kernel doc to match sources

Signed-off-by: Ronny Schmatzler <schmatzler@googlemail.com>
ion: fix ION_HEAP_<xxx>_MASK definitions

Signed-off-by: Iliyan Malchev <malchev@google.com>
Signed-off-by: Ronny Schmatzler <schmatzler@googlemail.com>