tty: serial: 8250: export early_serial8250_setup function

8250-like uart driver may call early_serial8250_setup to
reuse 8250_early.c character output function.
Signed-off-by: NEddie Huang <eddie.huang@mediatek.com>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_early.c

@@ -131,7 +131,7 @@ static void __init init_port(struct earlycon_device *device)
 	serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB);
 }
 
-static int __init early_serial8250_setup(struct earlycon_device *device,
+int __init early_serial8250_setup(struct earlycon_device *device,
 					 const char *options)
 {
 	if (!(device->port.membase || device->port.iobase))

include/linux/serial_8250.h

@@ -137,6 +137,8 @@ extern int early_serial_setup(struct uart_port *port);
 
 extern unsigned int serial8250_early_in(struct uart_port *port, int offset);
 extern void serial8250_early_out(struct uart_port *port, int offset, int value);
+extern int early_serial8250_setup(struct earlycon_device *device,
+					 const char *options);
 extern void serial8250_do_set_termios(struct uart_port *port,
 		struct ktermios *termios, struct ktermios *old);
 extern int serial8250_do_startup(struct uart_port *port);