regulator, mc13xxx: Remove pointless test for unsigned less than zero

The variable 'val' is a 'unsigned int', so it can never be less than zero.
This fact makes the "val < 0" part of the test done in BUG_ON() in
mc13xxx_regulator_get_voltage() rather pointles since it can never have
any effect.
This patch removes the pointless test.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/mc13xxx-regulator-core.c

@@ -174,7 +174,7 @@ static int mc13xxx_regulator_get_voltage(struct regulator_dev *rdev)
 
 	dev_dbg(rdev_get_dev(rdev), "%s id: %d val: %d\n", __func__, id, val);
 
-	BUG_ON(val < 0 || val > mc13xxx_regulators[id].desc.n_voltages);
+	BUG_ON(val > mc13xxx_regulators[id].desc.n_voltages);
 
 	return mc13xxx_regulators[id].voltages[val];
 }