Fix SCSI target off-by-one with vioscsi

Assign max_target as the controller ID instead of zero, so that it does
not obscure the device located at SCSI ID zero (like a disk) from being
probed by scsi_probe_bus().

Copy the target requested onto the wire without decrementing it by one.

Index: pci/vioscsi.c
===================================================================
RCS file: /cvsroot/src/sys/dev/pci/vioscsi.c,v
retrieving revision 1.21
diff -u -p -r1.21 vioscsi.c
--- pci/vioscsi.c	13 Apr 2019 06:17:33 -0000	1.21
+++ pci/vioscsi.c	11 Jul 2020 23:22:37 -0000
@@ -194,7 +194,7 @@ vioscsi_attach(device_t parent, device_t
 	chan->chan_channel = 0;
 	chan->chan_ntargets = MIN(max_target, 16);	/* cap reasonably */
 	chan->chan_nluns = MIN(max_lun, 1024);		/* cap reasonably */
-	chan->chan_id = 0;
+	chan->chan_id = max_target;
 	chan->chan_flags = SCSIPI_CHAN_NOSETTLE;
 
 	config_found(self, &sc->sc_channel, scsiprint);
@@ -318,7 +318,7 @@ vioscsi_scsipi_request(struct scsipi_cha
 	}
 
 	req->lun[0] = 1;
-	req->lun[1] = periph->periph_target - 1;
+	req->lun[1] = periph->periph_target;
 	req->lun[2] = 0x40 | ((periph->periph_lun >> 8) & 0x3F);
 	req->lun[3] = periph->periph_lun & 0xFF;
 	memset(req->lun + 4, 0, 4);