target: Make core_scsi3_update_and_write_aptpl return sense_reason_t

Fix up sense_reason_t breakage in core_scsi3_update_and_write_aptpl()
from recent conversion to use local scope memory allocation.

Reported as sparse warnings: (new ones prefixed by >>) by Fengguang:

>> drivers/target/target_core_pr.c:2069:57: sparse: incorrect type in
>> return expression (different base types)
   drivers/target/target_core_pr.c:2069:57:    expected restricted sense_reason_t
   drivers/target/target_core_pr.c:2069:57:    got int
>> drivers/target/target_core_pr.c:2179:21: sparse: incorrect type in
>> assignment (different base types)
   drivers/target/target_core_pr.c:2179:21:    expected restricted sense_reason_t [assigned] [usertype] ret
   drivers/target/target_core_pr.c:2179:21:    got int
>> drivers/target/target_core_pr.c:2197:13: sparse: incorrect type in
>> assignment (different base types)
   drivers/target/target_core_pr.c:2197:13:    expected restricted sense_reason_t [assigned] [usertype] ret
   drivers/target/target_core_pr.c:2197:13:    got int
   drivers/target/target_core_pr.c:1245:28: sparse: context imbalance in '__core_scsi3_free_registration' - unexpected unlock

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>