xfsprogs: suggest "-d" option for repair of RO mount

xfsprogs: suggest "-d" option for repair of RO mount

We can offer the suggestion of a "-d" repair, if we're
in single-user mode with i.e. the root fs mounted readonly.

This change suggests -d to repair any RO mounted fs.

e2fsck allows this, and users are used to being able to
do it in single-user mode.  A separate patch will recommend
a reboot after repair completes.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>