[Intel-gfx] [PATCH] drm/i915: Fix and clean BDW PCH identification

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 5616
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -2              353/353              351/353
ILK                                  200/200              200/200
SNB                                  400/422              400/422
IVB                                  487/487              487/487
BYT                                  296/296              296/296
HSW                                  508/508              508/508
BDW                                  401/402              401/402
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
*PNV  igt_gen3_render_linear_blits      PASS(2, M25M23)      NRUN(1, M23)
*PNV  igt_gen3_render_mixed_blits      PASS(2, M25M23)      CRASH(1, M23)
Note: You need to pay more attention to line start with '*'