target/sbc: Check that the LBA and number of blocks are correct in VERIFY

This patch extracts LBA + sectors for VERIFY, and adds a goto check_lba
to perform the end-of-device checking.

(Update patch to drop lba_check usage - nab)

Signed-off-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>