igb: move the generic copper link setup code into e1000_phy.c

This patch moves the generic portion of the copper link setup into a
seperate function in e1000_phy.c.  This helps to reduce the size of
copper_link_setup_82575 and make it a bit more readable.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>