igc: Remove IGC_MDIC_INT_EN definition

IGC_MDIC_INT_EN definition is not used. This patch comes to tidy up the
driver code.
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -610,7 +610,6 @@
 #define IGC_MDIC_OP_WRITE	0x04000000
 #define IGC_MDIC_OP_READ	0x08000000
 #define IGC_MDIC_READY		0x10000000
-#define IGC_MDIC_INT_EN		0x20000000
 #define IGC_MDIC_ERROR		0x40000000
 
 #define IGC_N0_QUEUE		-1