drm/amd/display: limit unbounded requesting to 5k

drm/amd/display: limit unbounded requesting to 5k

Unbounded requesting is unsupported on pipe split modes
and this change prevents us running into such a situation
with wide modes.

Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>