drm/amd/display: correct hostvm flag

[Why]
Hostvm should be enabled/disabled accordding to the status of
riommu_active, but hostvm always be disabled on DCN31 which causes
underflow

[How]
Set correct hostvm flag on DCN31
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Sherry Wang <Yao.Wang1@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/resource/dcn31/dcn31_resource.c

@@ -892,7 +892,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 	.disable_z10 = true,
 	.enable_legacy_fast_update = true,
 	.enable_z9_disable_interface = true, /* Allow support for the PMFW interface for disable Z9*/
-	.dml_hostvm_override = DML_HOSTVM_OVERRIDE_FALSE,
+	.dml_hostvm_override = DML_HOSTVM_NO_OVERRIDE,
 	.using_dml2 = false,
 };