xfs: add missing break in xfs_parseargs()

Commit 2e74af0e ("xfs: convert mount option parsing to tokens")
missed a 'break;' in xfs_parseargs() which causes mount to fail with
"-o pqnoenforce" option when mounting a v4 filesystem. xfs/050
catches this failure:

XFS (vda6): Super block does not support project and group quota together

Fixes: 2e74af0e ("xfs: convert mount option parsing to tokens")
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>