drm/amd/display: Revert DCN2.1 dram_clock_change_latency update

[Why]
New value breaks VSR on high refresh panels, reverting until a fix is developed

Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>