igc: Remove unused MII_CR_SPEED

Force PHY speed not supported for i225 devices.
MII_CR_SPEED masks not in use in i225 device and can be removed.
Signed-off-by: NSasha Neftin <sasha.neftin@intel.com>
Tested-by: NDvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_defines.h

@@ -442,9 +442,6 @@
 #define MII_CR_POWER_DOWN	0x0800  /* Power down */
 #define MII_CR_AUTO_NEG_EN	0x1000  /* Auto Neg Enable */
 #define MII_CR_LOOPBACK		0x4000  /* 0 = normal, 1 = loopback */
-#define MII_CR_SPEED_1000	0x0040
-#define MII_CR_SPEED_100	0x2000
-#define MII_CR_SPEED_10		0x0000
 
 /* PHY Status Register */
 #define MII_SR_LINK_STATUS	0x0004 /* Link Status 1 = link */