igc: Remove MULR mask define

Multiple Tx Data Read Requests is hardware pipeline feature and
is not controlled by software
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -284,7 +284,6 @@
 #define IGC_TCTL_CT		0x00000ff0 /* collision threshold */
 #define IGC_TCTL_COLD		0x003ff000 /* collision distance */
 #define IGC_TCTL_RTLC		0x01000000 /* Re-transmit on late collision */
-#define IGC_TCTL_MULR		0x10000000 /* Multiple request support */
 
 /* Flow Control Constants */
 #define FLOW_CONTROL_ADDRESS_LOW	0x00C28001