Move ReadDmaBufs() into dmabufinfo.cpp am: 3e598e47d9 am: 3e0496da85 am: 2d0a874040

Original change: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/2010716

Change-Id: I0497d3ea754eb7013a37871a4c16477a23864690