DX12/SM6 Sampler Counts increased for empty materials between 5.1 and 5.2

While not a major issue in and of itself, this can cause considerable headaches for materials where sampler counts in 5.1 were at 15/16 or 16/16 and when upgrading to 5.2 are now exceeding the built-in limits.

1. With the launcher build of 5.1, create a new material. Enable the Platform Stats panel, and note the number of samplers. (Should be 3/16)
2. With the launcher build of 5.2, create a new material. Enable the Platform Stats panel, and note the number of samplers. (Should be 5/16)