target: Fix VERIFY and WRITE VERIFY command parsing

Use the value of the BYTCHK field to determine the size of the
Data-Out buffer. For VERIFY, honor the VRPROTECT, DPO and FUA
fields. This patch avoids that LIO complains about a mismatch
between the expected transfer length and the SCSI CDB length
if the value of the BYTCHK field is 0.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Max Lohrmann <post@wickenrode.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>