Revert "mm-video: Add the ability to use PMEM while using TARGET_USES_ION := true"

This reverts commit 4dfa293111d4d9f3cf25b3c582228ce36a4d61a8.
mm-video: vdec: Use GRALLOC_USAGE_PRIVATE_ADSP_HEAP instead of no more defined GRALLOC_USAGE_PRIVATE_CAMERA_HEAP
Change-Id: I1c698f27274adda5972d2de3bfddf7ab7ed9041e