drm/amd/display: Add delay to improve LTTPR UHBR interop

drm/amd/display: Add delay to improve LTTPR UHBR interop

[ Upstream commit 10839ee6a977ed1f7d0f4deb29f2d7e5d1f2a9dd ]

[WHY]
Avoid race condition which puts LTTPR into bad state during UHBR LT.

[HOW]
Delay 30ms between starting UHBR TPS1 PHY output and sending TPS1 via DPCD.

Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>