radv/gfx10: add radv_device::use_ngg

Trivial.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
40 jobs for !2019 with gfx10_add_use_ngg in 3 minutes and 26 seconds (queued for 3 seconds)
merge request