xfs: use -f option for xfs_repair a fs image

xfs: use -f option for xfs_repair a fs image

xfs/020 need -f option, or it'll be fail on 4k sector device.

Add -f option for xfs/032 for safe and better.

There're some cases use _check_xfs_filesystem(), or others
function which call this function to check a regular file.
That's will fail when the regular file on a 4k sector device.
For example xfs/250.

So I change _check_xfs_filesystem(), add -f option to xfs_repair,
when the $device is a file.

Signed-off-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>