tests/drm_lib.sh: Skip when i915 debugfs wasn't found
tests/drm_lib.sh: Skip when i915 debugfs wasn't found

Instead of failing. We might want to move this into i915 tests
eventually, but this is good for now.

v2: Use the correct exit code (Derek) and use the new symbolic values
Thomas added.

Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools