Revert "libgralloc: Change CAMERA_HEAP to ADSP_HEAP"

This reverts commit 9f5423c18e048744e6640b96883b2f57195c096e.
gralloc: Allow legacy devices to use PMEM for ADSP (camera).

Partially bring back PMEM support for legacy devices having proprietary camera
libraries stuck in PMEM. This change allows these devices to continue using
PMEM for the camera, and ION for everything else.

Based on https://github.com/Blefish/android_hardware_qcom_display-caf/commit/41c51319b03cab926a64964d29296b1127274ee0