gralloc: Fix issue with mmap/munmap meta due to reserved size am: c9a0d7b113 am: eedb45ab30 am: 58137990bb am: 28c872a6d2

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/qcom/sm8150/display/+/19355927

Change-Id: Ic25802d5d811eaeea76b2c6bf1dde02f928d64e6
Signed-off-by: Automerger Merge Worker <[email protected]>