e1000e: Drop a useless statement

err is set again a few lines below.

Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>