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/arch/arm/mach-davinci/da850_lowlevel.c b/arch/arm/mach-davinci/da850_lowlevel.c
index 6994ded..759c937 100644
--- a/arch/arm/mach-davinci/da850_lowlevel.c
+++ b/arch/arm/mach-davinci/da850_lowlevel.c
@@ -290,7 +290,7 @@
 	board_gpio_init();
 
 #if !CONFIG_IS_ENABLED(DM_SERIAL)
-	NS16550_init((struct ns16550 *)(CONFIG_SYS_NS16550_COM1),
+	ns16550_init((struct ns16550 *)(CONFIG_SYS_NS16550_COM1),
 		     CONFIG_SYS_NS16550_CLK / 16 / CONFIG_BAUDRATE);
 #endif
 	/*