mv643xx_eth: Check ETH_INT_CAUSE_STATE bit

Commit 468d09f8946d40228c56de26fe4874b2f98067ed masked the "state"
interrupt (bit 20 of the cause register). This results in Radstone's
PPC7D repeatedly re-entering the interrupt routine, locking up the
board. The following patch returns the required handling for this
interrupt.

Signed-off-by: Martyn Welch <martyn.welch@radstone.co.uk>
Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 456d1e1..34288fe 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -534,7 +534,7 @@
 	}
 
 	/* PHY status changed */
-	if (eth_int_cause_ext & ETH_INT_CAUSE_PHY) {
+	if (eth_int_cause_ext & (ETH_INT_CAUSE_PHY | ETH_INT_CAUSE_STATE)) {
 		struct ethtool_cmd cmd;
 
 		if (mii_link_ok(&mp->mii)) {