[Intel-gfx] [PATCH] drm/i915: Simplify the way BC bifurcation state consistency is kept

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 5925
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -2              282/282              280/282
ILK                                  308/308              308/308
SNB                                  307/307              307/307
IVB                                  375/375              375/375
BYT                                  294/294              294/294
HSW                                  385/385              385/385
BDW                                  315/315              315/315
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 PNV  igt_gem_userptr_blits_minor-normal-sync      DMESG_WARN(2)PASS(3)      DMESG_WARN(2)
*PNV  igt_gem_userptr_blits_minor-unsync-normal      PASS(4)      DMESG_WARN(1)PASS(1)
Note: You need to pay more attention to line start with '*'