drm/amd/display: Fix refresh rate issue on Club 3D

Recently we introduced a patch for fixing an MST issue, but it caused a
regression on Club 3D since we could not set a refresh rate higher than
60Hz. This commit fixes this issue by adding a proper check after
validating the stream.

Fixes: f04d275d ("drm/amd/display: add mst port output bw check")
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>