igb: fix stats for i210 rx_fifo_errors

RQDPC on i210/i211 is R/W not ReadClear. Clear after reading.

Signed-off-by: Todd Fujinaka <todd.fujinaka@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>