drm/nouveau/gr/gf100-: change gf108_gr_fwif from global to static

Smatch reports this issue
gf108.c:147:1: warning: symbol 'gf108_gr_fwif'
  was not declared. Should it be static?

gf108_gr_fwif is only used in gf108.c.  Single
file variables should not be global so change
gf108_gr_fwif's storage-class specifier to static.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220418152810.3280502-1-trix@redhat.com

drivers/gpu/drm/nouveau/nvkm/engine/gr/gf108.c

@@ -143,7 +143,7 @@ gf108_gr = {
 	}
 };
 
-const struct gf100_gr_fwif
+static const struct gf100_gr_fwif
 gf108_gr_fwif[] = {
 	{ -1, gf100_gr_load, &gf108_gr },
 	{ -1, gf100_gr_nofw, &gf108_gr },