regulator: helper: Document ramp_delay parameter of regulator_set_ramp_delay_regmap()

With W=1:

    drivers/regulator/helpers.c:947: warning: Function parameter or member 'ramp_delay' not described in 'regulator_set_ramp_delay_regmap'

Fix it by documenting the parameter.

Fixes: fb8fee9e ("regulator: Add regmap helper for ramp-delay setting")
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1686881298-28333-1-git-send-email-cy_huang@richtek.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/helpers.c

@@ -952,6 +952,7 @@ EXPORT_SYMBOL_GPL(regulator_find_closest_bigger);
  * regulator_set_ramp_delay_regmap - set_ramp_delay() helper
  *
  * @rdev: regulator to operate on
+ * @ramp_delay: ramp-rate value given in units V/S (uV/uS)
  *
  * Regulators that use regmap for their register I/O can set the ramp_reg
  * and ramp_mask fields in their descriptor and then use this as their