igc: Remove unused MDIC_DEST mask

Formally Destination bit should be kept reserved to
support legacy drivers and ignore on write/read
operation
Not applicable for i225 parts
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -510,7 +510,6 @@
 #define IGC_MDIC_READY		0x10000000
 #define IGC_MDIC_INT_EN		0x20000000
 #define IGC_MDIC_ERROR		0x40000000
-#define IGC_MDIC_DEST		0x80000000
 
 #define IGC_N0_QUEUE		-1