[Intel-gfx] [PATCH 2/2] drm/i915/skl: Add support for edp1.4 low vswing

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 5821
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -3              281/281              278/281
ILK                                  308/308              308/308
SNB                 -1              326/326              325/326
IVB                                  380/380              380/380
BYT                                  294/294              294/294
HSW                                  387/421              387/421
BDW                 -1              316/316              315/316
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
*PNV  igt_gem_userptr_blits_minor-unsync-interruptible      PASS(3)      DMESG_WARN(1)PASS(1)
 PNV  igt_gem_userptr_blits_minor-unsync-normal      DMESG_WARN(3)PASS(1)      DMESG_WARN(1)PASS(1)
*PNV  igt_gen3_render_mixed_blits      PASS(5)      CRASH(1)PASS(1)
*SNB  igt_kms_plane_plane-panning-bottom-right-pipe-B-plane-1      DMESG_WARN(12)PASS(4)      TIMEOUT(1)PASS(1)
*BDW  igt_gem_gtt_hog      PASS(10)      DMESG_WARN(1)PASS(1)
Note: You need to pay more attention to line start with '*'