dm raid: fix false -EBUSY when handling check/repair message

Sending a check/repair message infrequently leads to -EBUSY instead of
properly identifying an active resync.  This occurs because
raid_message() is testing recovery bits in a racy way.

Fix by calling decipher_sync_action() from raid_message() to properly
identify the idle state of the RAID device.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>