igb: make local functions static and remove dead code

Based on Stephen Hemminger's original patch.
Make local functions static, and remove unused functions.

Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ethernet/intel/igb/e1000_82575.c
Simple merge

diff --cc drivers/net/ethernet/intel/igb/e1000_82575.h
Simple merge

diff --cc drivers/net/ethernet/intel/igb/e1000_i210.c
Simple merge

diff --cc drivers/net/ethernet/intel/igb/e1000_i210.h
Simple merge

diff --cc drivers/net/ethernet/intel/igb/e1000_phy.c
Simple merge

diff --cc drivers/net/ethernet/intel/igb/e1000_phy.h
Simple merge

diff --cc drivers/net/ethernet/intel/igb/igb.h
Simple merge

diff --cc drivers/net/ethernet/intel/igb/igb_ptp.c
Simple merge