drm/amdkfd: To enable traps for GC_11_0_4 and up

Flag trap_en should be enabled for trap handler.

Signed-off-by: Ruili Ji <ruiliji2@amd.com>
Signed-off-by: Aaron Liu <aaron.liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>