ARM: OMAP: Add return value check for input_register_device()

drivers/cbus/retu-pwrbutton.c:100: warning: ignoring return value of 'input_register_device', declared with attribute warn_unused_result
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/cbus/retu-pwrbutton.c

@@ -97,9 +97,7 @@ static int __init retubutton_init(void)
 	pwrbtn_dev->keybit[BIT_WORD(KEY_POWER)] = BIT_MASK(KEY_POWER);
 	pwrbtn_dev->name = "retu-pwrbutton";
 
-	input_register_device(pwrbtn_dev);
-
-	return 0;
+	return input_register_device(pwrbtn_dev);
 }
 
 /**