Make mediaextractor use hidl memory allocated by
hidl allocator, instead of constructing hidl memory
from IMemory.

bug: 112766913
bug: 111407253
Change-Id: I7902f18768005c995925bc9a7947299e9988b68a
(Needed for internal commit I39e131718ea41f9cb23177c28213ddf7b7741338)