ANDROID: sdcardfs: Fix gid issue

We were already calculating most of these values,
and erroring out because the check was confused by this.
Instead of recalculating, adjust it as needed.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 36160015
Change-Id: I9caf3e2fd32ca2e37ff8ed71b1d392f1761bc9a9