drm/amd/display: Update DRAM watermark before checking to update TTU

drm/amd/display: Update DRAM watermark before checking to update TTU

[Why]
In most cases, DRAM watermark is large enough that the result of the
condition to increase TTU doesn't change after DRAM watermark is
increased. However, there is are cases where the condition fails and
becomes true after DRAM watermark is increased. This results in minTTU <
DRAM watermarks which leads to PSR hang since p-state is requested but
not allowed.

[How]
Check whether to update TTU after DRAM watermark is updated.

Signed-off-by: Jaehyun Chung <jaehyun.chung@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>