intel: Do not assert on unknown chips in drm_intel_decode_context_alloc
There is this long standing nit of igt/tools/intel_error_decode asserting when you feed it an error state from a GPU the local libdrm does not know of.
To fix this I need a tweak in drm_intel_decode_context_alloc to make it not assert but just return NULL (which seems an already possible return value).
Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Cc: Zbigniew Kempczyński zbigniew.kempczynski@intel.com