dm raid: fix processing of max_recovery_rate constructor flag

__CTR_FLAG_MIN_RECOVERY_RATE was used instead of __CTR_FLAG_MAX_RECOVERY_RATE
thus causing max_recovery_rate to be rejected in case min_recovery_rate
was already set.

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