serial: Rename ns16550 functions to lower case

Lower case should be used for function names. Update this driver and its
callers accordingly.

Signed-off-by: Simon Glass <sjg@chromium.org>

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
diff --git a/board/freescale/p1010rdb/spl.c b/board/freescale/p1010rdb/spl.c
index c015a6b..35b95e0 100644
--- a/board/freescale/p1010rdb/spl.c
+++ b/board/freescale/p1010rdb/spl.c
@@ -44,7 +44,7 @@
 	plat_ratio >>= 1;
 	gd->bus_clk = CONFIG_SYS_CLK_FREQ * plat_ratio;
 
-	NS16550_init((struct ns16550 *)CONFIG_SYS_NS16550_COM1,
+	ns16550_init((struct ns16550 *)CONFIG_SYS_NS16550_COM1,
 		     gd->bus_clk / 16 / CONFIG_BAUDRATE);
 
 #ifdef CONFIG_SPL_MMC_BOOT