e1000e: fix double initialization in blink path

The kernel goes BUG() at the time 'ethtool -p eth0 3' comes
back, which is due to adapter->led_blink_task initialized
several times.  At the time it is still running this results
in a corrupted task_list of the associated workqueue.

The fix is to move the workqueue initialization to the
probe function instead.

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>