drm/nouveau/mc/ga100: make ga100_mc_device static

Make ga100_mc_device static as it isn't exported, to
fix the following sparse warning:

drivers/gpu/drm/nouveau/nvkm/subdev/mc/ga100.c:51:1: warning: symbol 'ga100_mc_device' was not declared. Should it be static?
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221229155249.669436-1-ben-linux@fluff.org

drivers/gpu/drm/nouveau/nvkm/subdev/mc/ga100.c

@@ -47,7 +47,7 @@ ga100_mc_device_enabled(struct nvkm_mc *mc, u32 mask)
 	return (nvkm_rd32(mc->subdev.device, 0x000600) & mask) == mask;
 }
 
-const struct nvkm_mc_device_func
+static const struct nvkm_mc_device_func
 ga100_mc_device = {
 	.enabled = ga100_mc_device_enabled,
 	.enable = ga100_mc_device_enable,