net/phy/mdio-i2c: Move header file to include/linux/mdio

In preparation for moving all MDIO drivers into drivers/net/mdio, move
the mdio-i2c header file into include/linux/mdio so it can be used by
both the MDIO driver and the SFP code which instantiates I2C MDIO
busses.

v2:
Add include/linux/mdio

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -15647,6 +15647,7 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/phy/phylink.c
 F:	drivers/net/phy/sfp*
+F:	include/linux/mdio/mdio-i2c.h
 F:	include/linux/phylink.h
 F:	include/linux/sfp.h
 K:	phylink\.h|struct\s+phylink|\.phylink|>phylink_|phylink_(autoneg|clear|connect|create|destroy|disconnect|ethtool|helper|mac|mii|of|set|start|stop|test|validate)

drivers/net/phy/mdio-i2c.c

@@ -10,10 +10,9 @@
  * of their settings.
  */
 #include <linux/i2c.h>
+#include <linux/mdio/mdio-i2c.h>
 #include <linux/phy.h>
 
-#include "mdio-i2c.h"
-
 /*
  * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
  * specified to be present in SFP modules.  These correspond with PHY

drivers/net/phy/sfp.c

@@ -7,6 +7,7 @@
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/jiffies.h>
+#include <linux/mdio/mdio-i2c.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
@@ -16,7 +17,6 @@
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 
-#include "mdio-i2c.h"
 #include "sfp.h"
 #include "swphy.h"