Fix to EDS3 tests for platforms that don't support mixed samples

Fix to EDS3 tests for platforms that don't support mixed samples

The EDS3 tests for rasterizationSamples that use the two-draws sequence
hit a condition where the framebuffer sample count does not match
the rasterization sample count. This is only valid usage on platforms
that implement VK_AMD_mixed_attachment_samples or
VK_NV_framebuffer_mixed_samples.

Affects:
dEQP-VK.pipeline.*.extended_dynamic_state.*

Components: Vulkan
VK-GL-CTS issue: 4220

Change-Id: I6e846a5c217656cc305b607d78c75a70d2e21fd7