regulator: hi6421v600: Remove unneeded *pmic from struct hi6421_spmi_reg_info

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: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210430085555.1127994-1-axel.lin@ingics.com


Signed-off-by: Mark Brown <broonie@kernel.org>