regulator: rc5t583: Remove unused fields from struct rc5t583_regulator_info

The *dev and *mfd of struct rc5t583_regulator_info are not used after convert
to use regmap, remove them.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>