tests/pm_rpm: add dpms-mode-unset{,-non}-lpsp subtests
tests/pm_rpm: add dpms-mode-unset{,-non}-lpsp subtests

These tests currently trigger WARNs on our Kernel. Let's make sure we
fix the bug and it never comes back.

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

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