itest: add missing break statements to evalexp()

The commit mentioned below replaced return statements inside a switch so
that other code could be called after the switch. However, it didn't add
any break statements, causing the cases to run together. Fix this.

Reported-by: Coverity (CID 132282, 132283)
Fixes: 7861204c ("itest: make memory access work under sandbox")
Signed-off-by: NStephen Warren <swarren@nvidia.com>

common/cmd_itest.c

@@ -64,9 +64,15 @@ static long evalexp(char *s, int w)
 			return 0;
 		}
 		switch (w) {
-		case 1: l = (long)(*(unsigned char *)buf);
-		case 2: l = (long)(*(unsigned short *)buf);
-		case 4: l = (long)(*(unsigned long *)buf);
+		case 1:
+			l = (long)(*(unsigned char *)buf);
+			break;
+		case 2:
+			l = (long)(*(unsigned short *)buf);
+			break;
+		case 4:
+			l = (long)(*(unsigned long *)buf);
+			break;
 		}
 		unmap_physmem(buf, w);
 		return l;