staging: panel: Fixed checkpatch warning about simple_strtoul()

Fixed the checkpatch warning about sing simple_strtoul instead of
kstrtoul() in panel.c.
Signed-off-by: Pelle Windestam <iceaway@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/panel/panel.c

@@ -1179,16 +1179,14 @@ static inline int handle_lcd_special_code(void)
 			break;
 
 		while (*esc) {
-			char *endp;
-
 			if (*esc == 'x') {
 				esc++;
-				lcd_addr_x = simple_strtoul(esc, &endp, 10);
-				esc = endp;
+				if (kstrtoul(esc, 10, &lcd_addr_x) < 0)
+					break;
 			} else if (*esc == 'y') {
 				esc++;
-				lcd_addr_y = simple_strtoul(esc, &endp, 10);
-				esc = endp;
+				if (kstrtoul(esc, 10, &lcd_addr_y) < 0)
+					break;
 			} else
 				break;
 		}