lib: Handle return error code of VbExDisplaySetDimension correctly.

The return value of VbExDisplaySetDimension should be handled as VbError_t,
which means we should print error message when it's not zero.
Also add the return code to debug message.

BRANCH=none
BUG=none
TEST=emerge-nyan coreboot chromeos-bootimage, enter recovery screen.
     Not seeing error messages anymore.

Change-Id: Icafdfd933d799e8496fedcf1633339065c6962a3
Reviewed-on: https://chromium-review.googlesource.com/200679
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
diff --git a/firmware/lib/vboot_display.c b/firmware/lib/vboot_display.c
index 669c4e8..6e0c93a 100644
--- a/firmware/lib/vboot_display.c
+++ b/firmware/lib/vboot_display.c
@@ -239,11 +239,11 @@
 				ret = VbExDisplaySetDimension(
 						image_info.width,
 						image_info.height);
-				if (!ret) {
+				if (ret) {
 					VBDEBUG(("VbExDisplaySetDimension"
-						 "(%d,%d): failed.\n",
+						 "(%d,%d): failed (%#x).\n",
 						 image_info.width,
-						 image_info.height));
+						 image_info.height, ret));
 				}
 			}