regulator: bd70528: Convert to use regulator_set_ramp_delay_regmap

Use regulator_set_ramp_delay_regmap instead of open-coded.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/20210522124250.2121076-1-axel.lin@ingics.com


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