dm: scsi: Adjust return value of scsi_exec()

Change this function to return an error number instead of true/false.
This allows us to return a proper error number.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index f3f8d31..80c5ce6 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -368,7 +368,7 @@
 	pccb->msgout[0] = SCSI_IDENTIFY; /* NOT USED */
 
 	pccb->datalen = 8;
-	if (scsi_exec(dev, pccb) != true)
+	if (scsi_exec(dev, pccb))
 		return 1;
 
 	*capacity = ((lbaint_t)pccb->pdata[0] << 24) |
@@ -393,7 +393,7 @@
 	pccb->msgout[0] = SCSI_IDENTIFY; /* NOT USED */
 
 	pccb->datalen = 16;
-	if (scsi_exec(dev, pccb) != true)
+	if (scsi_exec(dev, pccb))
 		return 1;
 
 	*capacity = ((uint64_t)pccb->pdata[0] << 56) |
@@ -499,7 +499,7 @@
 	pccb->pdata = (unsigned char *)&tempbuff;
 	pccb->datalen = 512;
 	scsi_setup_inquiry(pccb);
-	if (scsi_exec(dev, pccb) != true) {
+	if (scsi_exec(dev, pccb)) {
 		if (pccb->contr_stat == SCSI_SEL_TIME_OUT) {
 			/*
 			  * selection timeout => assuming no
@@ -530,7 +530,7 @@
 
 	pccb->datalen = 0;
 	scsi_setup_test_unit_ready(pccb);
-	if (scsi_exec(dev, pccb) != true) {
+	if (scsi_exec(dev, pccb)) {
 		if (dev_desc->removable) {
 			dev_desc->type = perq;
 			goto removable;