[Intel-gfx] [PATCH] drm/i915: Use pipe_config's cpu_transcoder for reading dp_mst hw state

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 5687
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                                  353/353              353/353
ILK                 -1              353/353              352/353
SNB                                  400/422              400/422
IVB              +2-1              485/487              486/487
BYT                                  296/296              296/296
HSW              +1-1              507/508              507/508
BDW                                  401/402              401/402
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
*ILK  igt_gem_unfence_active_buffers      PASS(2, M26)      DMESG_WARN(1, M26)
 IVB  igt_gem_pwrite_pread_snooped-pwrite-blt-cpu_mmap-performance      DMESG_WARN(6, M34M21)PASS(8, M4M34)      PASS(1, M34)
 IVB  igt_gem_storedw_batches_loop_normal      DMESG_WARN(5, M34M4)PASS(15, M34M4M21)      PASS(1, M34)
 IVB  igt_gem_storedw_batches_loop_secure-dispatch      DMESG_WARN(1, M34)PASS(6, M34M4)      DMESG_WARN(1, M34)
*HSW  igt_gem_pwrite_pread_display-copy-performance      PASS(5, M40M20)      DMESG_WARN(1, M40)
 HSW  igt_gem_pwrite_pread_snooped-pwrite-blt-cpu_mmap-performance      DMESG_WARN(1, M40)PASS(19, M40M20)      PASS(1, M40)
Note: You need to pay more attention to line start with '*'