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/serial_ks8695.c b/drivers/serial/serial_ks8695.c
index 60e8007..8b1c974 100644
--- a/drivers/serial/serial_ks8695.c
+++ b/drivers/serial/serial_ks8695.c
@@ -102,13 +102,6 @@
 	return 0;
 }
 
-static void ks8695_serial_puts(const char *s)
-{
-	char c;
-	while ((c = *s++) != 0)
-		serial_putc(c);
-}
-
 static int ks8695_serial_getc(void)
 {
 	volatile struct ks8695uart *uartp = KS8695_UART_ADDR;
@@ -124,7 +117,7 @@
 	.stop	= NULL,
 	.setbrg	= ks8695_serial_setbrg,
 	.putc	= ks8695_serial_putc,
-	.puts	= ks8695_serial_puts,
+	.puts	= default_serial_puts,
 	.getc	= ks8695_serial_getc,
 	.tstc	= ks8695_serial_tstc,
 };