drm/nouveau/gsp: remove extraneous ; after mutex

The mutex field has two following semicolons, replace this with just
one semicolon.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240917120856.1877733-1-colin.i.king@gmail.com

drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h

@@ -210,7 +210,7 @@ struct nvkm_gsp {
 	} *rm;
 
 	struct {
-		struct mutex mutex;;
+		struct mutex mutex;
 		struct idr idr;
 	} client_id;