drm/amdgpu: Fix implicit assumtion in gfx11 debug flags

Gfx11 debug flags mask is currently set with an implicit assumption that
no other mqd update flags exist. This needs to be fixed with newly
introduced flag UPDATE_FLAG_IS_GWS by the previous patch.

Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>