efi: payload: only init usb if necessary

Up until now the call to initialize the USB subsystem was hardcoded
for U-Boot running as an EFI payload. This was used to enable the
use of a USB keyboard in the U-Boot shell. However not all boards
might need this functionality. As initializing the USB subsystem can
take a considerable amount of time (several seconds on some boards),
we now initialize the USB subsystem only if U-Boot is configured to
use USB keyboards.
Signed-off-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NChristian Gmeiner <christian.gmeiner@gmail.com>

arch/x86/cpu/efi/payload.c

@@ -166,7 +166,8 @@ int reserve_arch(void)
 int last_stage_init(void)
 {
 	/* start usb so that usb keyboard can be used as input device */
-	usb_init();
+	if (CONFIG_IS_ENABLED(USB_KEYBOARD))
+		usb_init();
 
 	return 0;
 }