Bluetooth: dtl1: Fix memleak in probe()

We currently leak the driver info structure if dtl1_config fails. If we add a
kfree() to dtl1_release to fix this, then dtl1_release and dtl1_detach are
identical so this merges both functions.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>