igc: Remove unused _I_PHY_ID define

_I_PHY_ID not in use. Clean up the code accordingly,
and get rid of the unused define
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Nechama Kraus <nechamax.kraus@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -605,9 +605,6 @@
 #define PHY_1000T_CTRL		0x09 /* 1000Base-T Control Reg */
 #define PHY_1000T_STATUS	0x0A /* 1000Base-T Status Reg */
 
-/* Bit definitions for valid PHY IDs. I = Integrated E = External */
-#define I225_I_PHY_ID		0x67C9DC00
-
 /* MDI Control */
 #define IGC_MDIC_DATA_MASK	0x0000FFFF
 #define IGC_MDIC_REG_MASK	0x001F0000