sfc: Replace MDIO spinlock with mutex

We never use MDIO in atomic context, so we don't need to spin.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index fb9327c..0aeaeda 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -724,7 +724,7 @@
  * @mac_op: MAC interface
  * @mac_address: Permanent MAC address
  * @phy_type: PHY type
- * @phy_lock: PHY access lock
+ * @mdio_lock: MDIO lock
  * @phy_op: PHY interface
  * @phy_data: PHY private data (including PHY-specific stats)
  * @mdio: PHY MDIO interface
@@ -806,7 +806,7 @@
 	unsigned char mac_address[ETH_ALEN];
 
 	enum phy_type phy_type;
-	spinlock_t phy_lock;
+	struct mutex mdio_lock;
 	struct efx_phy_operations *phy_op;
 	void *phy_data;
 	struct mdio_if_info mdio;