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/mcfuart.c b/drivers/serial/mcfuart.c
index 00a7114..8ea9af0 100644
--- a/drivers/serial/mcfuart.c
+++ b/drivers/serial/mcfuart.c
@@ -87,13 +87,6 @@
 	uart->utb = c;
 }
 
-static void mcf_serial_puts(const char *s)
-{
-	while (*s) {
-		serial_putc(*s++);
-	}
-}
-
 static int mcf_serial_getc(void)
 {
 	volatile uart_t *uart = (volatile uart_t *)(CONFIG_SYS_UART_BASE);
@@ -136,7 +129,7 @@
 	.stop	= NULL,
 	.setbrg	= mcf_serial_setbrg,
 	.putc	= mcf_serial_putc,
-	.puts	= mcf_serial_puts,
+	.puts	= default_serial_puts,
 	.getc	= mcf_serial_getc,
 	.tstc	= mcf_serial_tstc,
 };