imx: imx_clock: uart: Add UART clock API

This patch adds an API to configure up the base UART clocks, taking a
bit-mask of silicon specific bits as an input from a higher layer in order
to direct the necessary clock source.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
diff --git a/plat/imx/common/include/imx_clock.h b/plat/imx/common/include/imx_clock.h
index f685a14..f1d1912 100644
--- a/plat/imx/common/include/imx_clock.h
+++ b/plat/imx/common/include/imx_clock.h
@@ -989,4 +989,7 @@
 
 void imx_clock_init(void);
 
+void imx_clock_enable_uart(unsigned int uart_id, uint32_t uart_clk_en_bits);
+void imx_clock_disable_uart(unsigned int uart_id);
+
 #endif /* __IMX_CLOCK_H__ */