drm/nouveau: gr/gk20a: Use firmware version 0

Tegra firmware doesn't actually use any version numbers and passing -1
causes the existing firmware binaries not to be found. Use version 0 to
find the correct files.

Fixes: ef16dc2 ("drm/nouveau/gr/gf100-: select implementation based on available FW")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/engine/gr/gk20a.c

@@ -352,7 +352,7 @@ gk20a_gr_load(struct gf100_gr *gr, int ver, const struct gf100_gr_fwif *fwif)
 
 static const struct gf100_gr_fwif
 gk20a_gr_fwif[] = {
-	{ -1, gk20a_gr_load, &gk20a_gr },
+	{ 0, gk20a_gr_load, &gk20a_gr },
 	{}
 };