[U-Boot] [PATCH 1/2][v2] lpuart: add a get_lpuart_clk function

[shh.xie at gmail.com]

From: Shaohui Xie <Shaohui.Xie at nxp.com>

It's not always true that LPUART clock is CONFIG_SYS_CLK_FREQ, this
patch provides a weak function get_lpuart_clk, so that the clock can be
ovreride on a specific board which uses different clock for LPUART.

Signed-off-by: Shaohui Xie <Shaohui.Xie at nxp.com>
---
changes in v2:
none.

 drivers/serial/serial_lpuart.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
index 042e9a2..beb4243 100644
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -170,9 +170,14 @@ static int lpuart_serial_probe(struct udevice *dev)
 }
 #else
 
+u32 __weak get_lpuart_clk(void)
+{
+	return CONFIG_SYS_CLK_FREQ;
+}
+
 static void _lpuart32_serial_setbrg(struct lpuart_fsl *base, int baudrate)
 {
-	u32 clk = CONFIG_SYS_CLK_FREQ;
+	u32 clk = get_lpuart_clk();
 	u32 sbr;
 
 	sbr = (clk / (16 * baudrate));
-- 
2.1.0.27.g96db324