Fixing xnnpack+qnnpack test (#355)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/355

Fixing all qnnpack tests. In addition to the broken test linked by mergen, there were many tests set to expect to fail.

This diff fixes all tests.

Reviewed By: digantdesai, kirklandsign

Differential Revision: D49068312

fbshipit-source-id: 48ba39828e13823cc6df979d9b109a96f6627466