i40e: removing unreachable code

The return value from i40e_shutdown_adminq() is always 0
(I40E_SUCCESS). So, the test for non-0 will never be true. Cleanup
by removing the test and debug print statement.

Change-ID: Ie51e8e37515c3e3a6a9ff26fa951d0e5e24343c1
Signed-off-by: Henry Tieman <henry.w.tieman@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>