xfs: refactor user/group quota chown in xfs_setattr_nonsize

Combine if tests to reduce the indentation levels of the quota chown
calls in xfs_setattr_nonsize.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>