Revert "ANDROID: Export functions to be used with dma_map_ops in modules"

The symbols exported by this commit were never used by external modules,
so just remove them as the exports are not needed (and cause merge
problems at times.)

Bug: 151050914
Bug: 203756332
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I926ad3cc732ec1db97fc4711962bc3902105dd25