trusty: Fix another reported misra violation

Change-Id: I822ccf5852dce4c01f98382cc393331f29e1e256
diff --git a/services/spd/trusty/trusty.c b/services/spd/trusty/trusty.c
index 6d9cc28..d6e5726 100644
--- a/services/spd/trusty/trusty.c
+++ b/services/spd/trusty/trusty.c
@@ -412,7 +412,7 @@
 	if (instr >> 24 == 0xeaU) {
 		INFO("trusty: Found 32 bit image\n");
 		aarch32 = true;
-	} else if (instr >> 8 == 0xd53810 || instr >> 16 == 0x9400) {
+	} else if (instr >> 8 == 0xd53810U || instr >> 16 == 0x9400U) {
 		INFO("trusty: Found 64 bit image\n");
 	} else {
 		NOTICE("trusty: Found unknown image, 0x%x\n", instr);