target: Export SPC inquiry emulation

Some target drivers might need to access the inquiry data
directly, without sending out the actual command.
So export these functions.

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

diff --cc drivers/target/target_core_spc.c
Simple merge

diff --cc include/target/target_core_backend.h
Simple merge