drivers:staging:android: Use mmput rather than mmput_async

* No good backport of mmput_async is available and my attempts
  at backporting it have failed.

Change-Id: I4309dd3e5c94e35cd35f40e548e731f2207e2cb9
Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>
Signed-off-by: Albert I <krascgq@outlook.co.id>
1 file changed