[inductor] Fix channels_last conv2d propagation when CuDNN is not found (#87266)
Fixes https://github.com/pytorch/torchdynamo/issues/1701
cc @jansel @lezcano @fdrocha @mlazos @voznesenskym @yanboliang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87266
Approved by: https://github.com/anijain2305, https://github.com/jansel, https://github.com/voznesenskym
