[WHY]
Z10 is should not be enabled by default on DCN31.

[HOW]
Using DC debug flags to disable Z10 by default on DCN31.
Reviewed-by: Eric Yang <Eric.Yang2@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Saaem Rizvi <syerizvi@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>