FROMLIST/BACKPORT: drm/amd/display: fix eDP fast bootup for pre-raven asic

[Why]
For fastboot, Bios will light up eDP before SW driver is loaded. SW
driver will check if eDP is lit by bios through reading the
BIOS_SCRATCH_3 register. If lit, SW driver will not power down eDP
power and phy to save time.

Definition of BIOS_SCRATCH_3 are missing for pre-raven asic. This
causes eDP fast boot to not work property. For some eDP panels, even
if dp tx sends NoVideoStream_flag =1 and dpcd 0x600=2, eDP rx may not
handle properly. This may cause a short flash on screen.

[How] Add definition of BIOS_SCRATCH_3 for all asic

Signed-off-by: hersen wu <hersenxs.wu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Acked-by: Yongqiang Sun <yongqiang.sun@amd.com>

(cherry picked from commit 10ce133f9d1912bd5247d2479b52ade036335297
 in git://people.freedesktop.org/~agd5f/linux

 branch:amd-staging-drm-next)

Conflicts:
          drivers/gpu/drm/amd/display/dc/dce120/dce120_resource.c
	  (context conflict only; no code change)

BUG=b:117532976
TEST=Build & Boot On Grunt

Change-Id: Ia82dce8347eb089aa24909e8282659e6dde98e56
Signed-off-by: Deepak Sharma <Deepak.Sharma@amd.com>
Reviewed-on: https://chromium-review.googlesource.com/1409881


Commit-Ready: Deepak Sharma <deepak.sharma@amd.com>
Tested-by: Deepak Sharma <deepak.sharma@amd.com>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>