ixgbe: Remove second instance of lan_id variable

This patch removes the redundant lan_id in the phy struct and uses
the bus version.  Both variables exist and intend to represent the
STATUS register LAN_ID field.  However, phy.lan_id is not bit shifted
so the phy.lan_id = 0x0 for LAN Id 0 and phy.lan_id = 0x4 for LAN Id 1.
Where bus.lan_id is bit shifted so bus.lan_id = 0x0 for LAN Id 0 and
bus.lan_id = 0x1 for LAN Id 1. There seems no need for the additional
lan_id variable and this should make the code less confusing.

Signed-off-by: Donald C Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>