bounds reads and writes are now reported correctly
even if they transfer 0 blocks.  Other errors are also reported correctly.

Testcase: sg_raw /dev/sdb 28 00 80 00 00 00 00 00 00 00
    should fail with ILLEGAL REQUEST / LBA OUT OF RANGE sense
    does not fail without the patch
    (still wrong with the patch, but better: the ASC is INVALID FIELD IN CDB)

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
|VC{›,x