target: Send UA upon LUN RESET tmr completion

SAM mandates that an BUS DEVICE RESET FUNCTION OCCURRED
UA needs to be send after a LUN RESET tmr has completed.

(Update to use target_ua_allocate_lun - hch)

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>