igb: update driver to use setup_timer function

igb was previously setting up all of the timer members itself.  It is
easier to just call setup_timer and reduce the calls to one line.

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>