Use rdev->regmap instead of pmic->regmap.
With this change, hi6421_spmi_regulator_disable can be removed and use
regulator_disable_regmap instead.
Signed-off-by: NAxel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210430085555.1127994-1-axel.lin@ingics.comSigned-off-by: NMark Brown <broonie@kernel.org>