mm: allow access fastrpc total_dma_kb sysfs am: 52299584f2 am: 91a336ff29 am: 951eff541e am: 9466f0a22b

Original change: https://android-review.googlesource.com/c/platform/hardware/google/pixel-sepolicy/+/1431713

Change-Id: I23ddacd82feb3ed884af2ead9b3883bb7b861540