drm/nouveau/disp: make gv100_disp_core_mthd_base static

The symbol is not used outside of the file, so mark it static.

Fixes the following warning:

./drivers/gpu/drm/nouveau/nvkm/engine/disp/gv100.c:591:1: warning:
symbol 'gv100_disp_core_mthd_base' was not declared. Should it be static?
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220924073957.4140388-1-ruanjinjie@huawei.com

drivers/gpu/drm/nouveau/nvkm/engine/disp/gv100.c

@@ -606,7 +606,7 @@ gv100_disp_curs = {
 	.user = 73,
 };
 
-const struct nvkm_disp_mthd_list
+static const struct nvkm_disp_mthd_list
 gv100_disp_core_mthd_base = {
 	.mthd = 0x0000,
 	.addr = 0x000000,