libdmabufheap: Do not fallback to ion when dma-buf exists am: d7fd440294 am: 0f1d4f9e68 am: d4ff3d3037

Original change: https://android-review.googlesource.com/c/platform/system/memory/libdmabufheap/+/2819907

Change-Id: I0c03ba9138c4d784de7f46db6d9448ec0e45b97e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>