mfd: Remove dead code from max8997-irq

We either hit one of the case's or the default in the switch statement
in get_i2c(), so the 'return ERR_PTR(-EINVAL);' at the end of the
function is just dead code - remove it.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/max8997-irq.c

@@ -58,8 +58,6 @@ static struct i2c_client *get_i2c(struct max8997_dev *max8997,
 	default:
 		return ERR_PTR(-EINVAL);
 	}
-
-	return ERR_PTR(-EINVAL);
 }
 
 struct max8997_irq_data {