xfs: don't log every time we clear the log incompat flags

There's no need to spam the logs every time we clear the log incompat
flags -- if someone is periodically using one of these features, they'll
be cleared every time the log tries to clean itself, which can get
pretty chatty:

$ dmesg | grep -i clear
[ 5363.894711] XFS (sdd): Clearing log incompat feature flags.
[ 5365.157516] XFS (sdd): Clearing log incompat feature flags.
[ 5369.388543] XFS (sdd): Clearing log incompat feature flags.
[ 5371.281246] XFS (sdd): Clearing log incompat feature flags.

These aren't high value messages either -- nothing's gone wrong, and
nobody's trying anything tricky.

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