xfs: don't retry repairs harder when EAGAIN is returned

Repair functions will not return EAGAIN -- if they were not able to
obtain resources, they should return EDEADLOCK (like the rest of online
fsck) to signal that we need to grab all the resources and try again.
Hence we don't need to deal with this case except as a debugging
assertion.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>