clk/qcom: apq8016: return valid rate when setting UART clock

clk/qcom: apq8016: return valid rate when setting UART clock

The clk_init_uart() helper always returns 0, but we're meant to return a
real clock rate. Given that we hardcode 115200 baud, just return the
clock rate that we set.

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>