regulator: qcom_smd: add regulator ops for pm8941 lnldo

After "regulator: qcom_smd: add list_voltage callback" patch adding
pm8941 lnldo regulators would bug on list_voltages as it is a fixed
regulator without any linear range.
This patch fixes that issue by adding dedicated ops for pm8941 lnldo
without list_voltages callback.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org # v4.6