serial: Use default_serial_puts() in drivers

Replace the in-place ad-hoc implementation of serial_puts() within
the drivers with default_serial_puts() call. This cuts down on the
code duplication quite a bit.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Tom Rini <trini@ti.com>
diff --git a/drivers/serial/s3c64xx.c b/drivers/serial/s3c64xx.c
index 9ab8a28..ea8d734 100644
--- a/drivers/serial/s3c64xx.c
+++ b/drivers/serial/s3c64xx.c
@@ -166,19 +166,13 @@
 	return uart->UTRSTAT & 0x1;
 }
 
-static void s3c64xx_serial_puts(const char *s)
-{
-	while (*s)
-		serial_putc(*s++);
-}
-
 static struct serial_device s3c64xx_serial_drv = {
 	.name	= "s3c64xx_serial",
 	.start	= s3c64xx_serial_init,
 	.stop	= NULL,
 	.setbrg	= s3c64xx_serial_setbrg,
 	.putc	= s3c64xx_serial_putc,
-	.puts	= s3c64xx_serial_puts,
+	.puts	= default_serial_puts,
 	.getc	= s3c64xx_serial_getc,
 	.tstc	= s3c64xx_serial_tstc,
 };