A WARN was mistakenly used when logging the unsupported extension
structs in getPhysicalDeviceFeatures2.

Bug: b/169966461
Change-Id: I9923c46ae83e6eb4ba70b76d401221fcf45c5734
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48989
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Sean Risser <srisser@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>