[Intel-gfx] [PATCH 3/3] drm/i915: Enable PSR by default.

[shuang.he at intel.com]

Tested-By: Intel Graphics QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 6691
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
ILK                                  302/302              302/302
SNB                                  312/316              312/316
IVB                                  343/343              343/343
BYT                 -2              287/287              285/287
HSW                                  380/380              380/380
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
*BYT  igt at gem_partial_pwrite_pread@reads      PASS(1)      FAIL(1)
*BYT  igt at gem_tiled_partial_pwrite_pread@reads      PASS(1)      FAIL(1)
Note: You need to pay more attention to line start with '*'