target: Further refactoring of core_scsi3_emulate_pro_register()

Use bool params when appropriate.

Eliminate unneeded pr_reg_e and type variables.

Just one goto label, so rename to 'out' from 'out_put_pr_reg'.

Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>