i40e: fix led blink toggle to enable steady state

Make sure to clear the GPIO blink field, instead of OR'ing against zero
if the field is already '1'.

Change-ID: Ie52a52abd48f6f52b20778a6b8b0c542dfc9245c
Signed-off-by: Matt Jared <matthew.a.jared@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>