Removed duplicate code.  Create ixgb_set_speed_duplex function to contain
duplicate code.
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NAuke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: NJohn Ronciak <john.ronciak@intel.com>