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/ns9750_serial.c b/drivers/serial/ns9750_serial.c
index cb545c4..85fc68a 100644
--- a/drivers/serial/ns9750_serial.c
+++ b/drivers/serial/ns9750_serial.c
@@ -100,19 +100,6 @@
 }
 
 /***********************************************************************
- * @Function: serial_puts
- * @Return: n/a
- * @Descr: writes non-zero string to the FIFO.
- ***********************************************************************/
-
-static void ns9750_serial_puts(const char *s)
-{
-	while (*s) {
-		serial_putc( *s++ );
-	}
-}
-
-/***********************************************************************
  * @Function: serial_getc
  * @Return: the character read
  * @Descr: performs only 8bit accesses to the FIFO. No error handling
@@ -215,7 +202,7 @@
 	.stop	= NULL,
 	.setbrg	= ns9750_serial_setbrg,
 	.putc	= ns9750_serial_putc,
-	.puts	= ns9750_serial_puts,
+	.puts	= default_serial_puts,
 	.getc	= ns9750_serial_getc,
 	.tstc	= ns9750_serial_tstc,
 };