drm/amdgpu/display: Fix a mistake in revert commit

[why]
It is to fix in try_disable_dsc() due to misrevert of
commit 338567d1 ("drm/amd/display: Fix MST BW calculation Regression")

[How]
Fix restoring minimum compression bw by 'max_kbps', instead of native bw 'stream_kbps'

Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>