Currently, loopback test may be skipped when resetting, but the test
result will still show as 'PASS', because the driver doesn't set
ETH_TEST_FL_FAILED flag. Fix it by setting the flag and
initializating the value to UNEXECUTED.

Fixes: 4c8dab1c ("net: hns3: reconstruct function hns3_self_test")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>