memtrack: Update AIDL memtrack hal documentation

Fix Memtrack GRAPHICS type definition to also inculde
GPU-mapped DMA-BUF memory.

Clarify SMAPS_UNACCOUTNED should also include memory
mapped with VM_PFNMAP set.

Bug: 192384999
Test: N/A
Change-Id: I5370efa731bc6307e4fe9b454796361e9a1ac5eb
Merged-In: I5370efa731bc6307e4fe9b454796361e9a1ac5eb
1 file changed