SCSI emulation: should tell the guest that we actually support thin provisioning

Signed-off-by: NRonnie Sahlberg <ronniesahlberg@gmail.com>
[Actually, we should report it only if discard_granularity is nonzero.
 Older SBC drafts assigned 0 to thin provisioning and 1 to thick
 (resource-provisioned, they call it).  Newer drafts assign respectively
 1 and 2 - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi-disk.c

@@ -628,7 +628,7 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
             outbuf[3] = buflen = 8;
             outbuf[4] = 0;
             outbuf[5] = 0x60; /* write_same 10/16 supported */
-            outbuf[6] = 0;
+            outbuf[6] = s->qdev.conf.discard_granularity ? 2 : 1;
             outbuf[7] = 0;
             break;
         }