regulator: rk808: Add apply_bit for BUCK3 on RK809

regulator: rk808: Add apply_bit for BUCK3 on RK809

Currently, RK809's BUCK3 regulator is modelled in the driver as a
configurable regulator with 0.5-2.4V voltage range. But the voltage
setting is not actually applied, because when bit 6 of
PMIC_POWER_CONFIG register is set to 0 (default), BUCK3 output voltage
is determined by the external feedback resistor. Fix this, by setting
bit 6 when voltage selection is set. Existing users which do not
specify voltage constraints in their device trees will not be affected
by this change, since no voltage setting is applied in those cases,
and bit 6 is not enabled.

Signed-off-by: Mikhail Rudenko <mike.rudenko@gmail.com>
Link: https://patch.msgid.link/20241017-rk809-dcdc3-v1-1-e3c3de92f39c@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>