tests/pc8: add modeset -stress-no-wait tests
tests/pc8: add modeset -stress-no-wait tests

Used to trigger a racing condition between mode setting and
enabling/disabling PC8. The modeset-lpsp-stress-no-wait test should
fail on Kernels without the fix I just wrote today.

Signed-off-by: Paulo Zanoni <cc0e04a2103c45cd195651d976f79813d0f66bdf@intel.com>

yipdw/intel-gpu-tools,dlespiau/checkmate-test-igt,dlespiau/checkmate-test-igt,chenxianqin/intel-gpu-tools,tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,rib/intel-gpu-tools,chenxianqin/intel-gpu-tools,erikarn/intel-gpu-tools,erikarn/intel-gpu-tools,rib/intel-gpu-tools,rib/intel-gpu-tools,erikarn/intel-gpu-tools,yipdw/intel-gpu-tools,rib/intel-gpu-tools,yipdw/intel-gpu-tools,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,dlespiau/checkmate-test-igt,chenxianqin/intel-gpu-tools,dlespiau/checkmate-test-igt,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,erikarn/intel-gpu-tools,yipdw/intel-gpu-tools