ralink: make sure a mii_bus is loaded before accesing its state

this caused a crash on boot

Signed-off-by: John Crispin <blogic@openwrt.org>

SVN-Revision: 43120

target/linux/ramips/patches-3.14/0035-NET-MIPS-add-ralink-SoC-ethernet-driver.patch

@@ -97,7 +97,7 @@ Index: linux-3.14.18/arch/mips/ralink/rt305x.c
 Index: linux-3.14.18/drivers/net/ethernet/Kconfig
 ===================================================================
 --- linux-3.14.18.orig/drivers/net/ethernet/Kconfig	2014-09-06 01:34:59.000000000 +0200
-+++ linux-3.14.18/drivers/net/ethernet/Kconfig	2014-10-30 09:43:22.196245753 +0100
++++ linux-3.14.18/drivers/net/ethernet/Kconfig	2014-10-30 11:09:42.442557047 +0100
 @@ -134,6 +134,7 @@
  source "drivers/net/ethernet/packetengines/Kconfig"
  source "drivers/net/ethernet/pasemi/Kconfig"
@@ -109,7 +109,7 @@ Index: linux-3.14.18/drivers/net/ethernet/Kconfig
 Index: linux-3.14.18/drivers/net/ethernet/Makefile
 ===================================================================
 --- linux-3.14.18.orig/drivers/net/ethernet/Makefile	2014-09-06 01:34:59.000000000 +0200
-+++ linux-3.14.18/drivers/net/ethernet/Makefile	2014-10-30 09:43:22.196245753 +0100
++++ linux-3.14.18/drivers/net/ethernet/Makefile	2014-10-30 11:09:42.442557047 +0100
 @@ -56,6 +56,7 @@
  obj-$(CONFIG_NET_PACKET_ENGINE) += packetengines/
  obj-$(CONFIG_NET_VENDOR_PASEMI) += pasemi/
@@ -1685,7 +1685,7 @@ Index: linux-3.14.18/drivers/net/ethernet/ralink/esw_rt3052.h
 Index: linux-3.14.18/drivers/net/ethernet/ralink/gsw_mt7620a.c
 ===================================================================
 --- /dev/null	1970-01-01 00:00:00.000000000 +0000
-+++ linux-3.14.18/drivers/net/ethernet/ralink/gsw_mt7620a.c	2014-10-30 09:02:08.735269671 +0100
++++ linux-3.14.18/drivers/net/ethernet/ralink/gsw_mt7620a.c	2014-10-30 11:05:31.228845263 +0100
 @@ -0,0 +1,569 @@
 +/*
 + *   This program is free software; you can redistribute it and/or modify
@@ -2197,7 +2197,7 @@ Index: linux-3.14.18/drivers/net/ethernet/ralink/gsw_mt7620a.c
 +	struct mt7620_gsw *gsw = (struct mt7620_gsw *) priv->soc->swpriv;
 +
 +	/* is the mt7530 internal or external */
-+	if (priv->mii_bus->phy_map[0x1f]) {
++	if (priv->mii_bus && priv->mii_bus->phy_map[0x1f]) {
 +		mt7530_probe(priv->device, gsw->base, NULL, 0);
 +		mt7530_probe(priv->device, NULL, priv->mii_bus, 1);
 +	} else {