regulator: qcom-labibb: Document soft start properties

Document properties to configure soft start and discharge resistor
for LAB and IBB respectively.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210119174421.226541-5-angelogioacchino.delregno@somainline.org


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