drm/amd/display: fix dcn315 dml detile overestimation

DML does not take the fact that dcn315 does not have enough detile
buffer to max all pipes. This change adds a workaround to apply
the same logic DC does when calculating detile buffer size in DML.

Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>