scsi: target: core: Avoid using lun_tg_pt_gp after unlock

core_alua_state_lba_dependent() currently uses lun->lun_tg_pt_gp without
holding the lun_tg_pt_gp_lock. The lock is taken in the caller, so obtain
the needed tg_pt_gp_id there instead.

Link: https://lore.kernel.org/r/20210728115353.2396-2-ddiss@suse.de


Cc: Hannes Reinecke <hare@suse.de>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>