Revert "iavf: Fix deadlock occurrence during resetting VF interface"

This change caused a regression with resetting while changing network
namespaces. By clearing the IFF_UP flag, the kernel now thinks it has
fully closed the device.

This reverts commit 0cc318d2.

Fixes: 0cc318d2 ("iavf: Fix deadlock occurrence during resetting VF interface")
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>