serial: msm: fix clock handling and pinctrl

serial: msm: fix clock handling and pinctrl

Use the modern helpers to fetch the clock and use the correct property
("clocks" instead of "clock"). Drop the call to pinctrl_select_state()
as no boards have a "uart" pinctrl state and this prints confusing
errors.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org> #qcs404
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>