This reverts commit 08f1c147.

Netdev is no longer being detached during reset, so this fix can be
reverted. We leave the removal of "hacky" IFF_UP flag update.
Signed-off-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>