igc: Remove unused MDICNFG register

The MDICNFG register from igc registers is not used so remove it.
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -10,7 +10,6 @@
 #define IGC_EECD		0x00010  /* EEPROM/Flash Control - RW */
 #define IGC_CTRL_EXT		0x00018  /* Extended Device Control - RW */
 #define IGC_MDIC		0x00020  /* MDI Control - RW */
-#define IGC_MDICNFG		0x00E04  /* MDC/MDIO Configuration - RW */
 #define IGC_CONNSW		0x00034  /* Copper/Fiber switch control - RW */
 #define IGC_I225_PHPM		0x00E14  /* I225 PHY Power Management */
 #define IGC_GPHY_VERSION	0x0001E  /* I225 gPHY Firmware Version */