usb: kbd: Prevent out of bound access

Scan code 0x39 is CapsLock, which is not a printable character and thus
is not covered by either usb_kbd_numkey_shifted[] or usb_kbd_numkey[].
Fix the scan code check to avoid looking it up in either of the arrays.

Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/common/usb_kbd.c b/common/usb_kbd.c
index cbb1995..d84865f 100644
--- a/common/usb_kbd.c
+++ b/common/usb_kbd.c
@@ -199,7 +199,7 @@
 		}
 	}
 
-	if ((scancode > 0x1d) && (scancode < 0x3a)) {
+	if ((scancode > 0x1d) && (scancode < 0x39)) {
 		/* Shift pressed */
 		if (modifier & (LEFT_SHIFT | RIGHT_SHIFT))
 			keycode = usb_kbd_numkey_shifted[scancode - 0x1e];