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> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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