m68k/q40: Add missing platform check before registering platform devices

On multi-platform kernels, the Q40/Q60 platform devices should be
registered when running on Q40/Q60 only. Else it may crash later.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/q40/config.c

@@ -334,6 +334,9 @@ static __init int q40_add_kbd_device(void)
 {
 	struct platform_device *pdev;
 
+	if (!MACH_IS_Q40)
+		return -ENODEV;
+
 	pdev = platform_device_register_simple("q40kbd", -1, NULL, 0);
 	if (IS_ERR(pdev))
 		return PTR_ERR(pdev);