serial: mcfuart: fix uart port index

Actually, using dev->seq value before probe to deduce the current
serial port index leads to reading an invalid seq value (-1).
So, getting dev->seq at probe time.

Signed-off-by: Angelo Durgehello <angelo.dureghello@timesys.com>
diff --git a/drivers/serial/mcfuart.c b/drivers/serial/mcfuart.c
index 066e5a1..b599064 100644
--- a/drivers/serial/mcfuart.c
+++ b/drivers/serial/mcfuart.c
@@ -85,6 +85,8 @@
 {
 	struct coldfire_serial_platdata *plat = dev->platdata;
 
+	plat->port = dev->seq;
+
 	return mcf_serial_init_common((uart_t *)plat->base,
 						plat->port, plat->baudrate);
 }
@@ -148,8 +150,6 @@
 		return -ENODEV;
 
 	plat->base = (uint32_t)addr_base;
-
-	plat->port = dev->seq;
 	plat->baudrate = gd->baudrate;
 
 	return 0;