regulator: core: Use a bitfield for continuous_voltage_range

Using a bitfield enables the compiler to lay out the structure more
efficiently when we have other boolean flags since multiple values can
be included in a single byte.
Signed-off-by: NMark Brown <broonie@kernel.org>

include/linux/regulator/driver.h

@@ -292,7 +292,7 @@ struct regulator_desc {
 			    const struct regulator_desc *,
 			    struct regulator_config *);
 	int id;
-	bool continuous_voltage_range;
+	unsigned int continuous_voltage_range:1;
 	unsigned n_voltages;
 	const struct regulator_ops *ops;
 	int irq;