e1000: fix kernel-doc argument being missing

Due to historical reason, 'phy_data' has never been included in the
kernel doc. Fix it so that the requirement could be fulfilled.
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from commit f03fed66)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/net/ethernet/intel/e1000/e1000_hw.c

@@ -2806,6 +2806,7 @@ static u16 e1000_shift_in_mdi_bits(struct e1000_hw *hw)
  * e1000_read_phy_reg - read a phy register
  * @hw: Struct containing variables accessed by shared code
  * @reg_addr: address of the PHY register to read
+ * @phy_data: pointer to the value on the PHY register
  *
  * Reads the value from a PHY register, if the value is on a specific non zero
  * page, sets the page first.