drm/amd/display: Renoir chroma viewport WA

[Why]
For unknown reason, immediate flip with host VM translation on NV12
surface will underflow on last row of PTE.

[How]
Hack chroma viewport height to make fetch one more row of PTE.
Note that this will cause hubp underflow on all video underlay
cases, but the underflow is not user visible since it is in
blank region.

Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>