fbcon: Make fbcon_registered_fb and fbcon_num_registered_fb static

fbcon_registered_fb and fbcon_num_registered_fb is not referred outside
drivers/video/fbdev/core/fbcon.c, so make them static.
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20230803020939.491-1-guozihua@huawei.com

drivers/video/fbdev/core/fbcon.c

@@ -103,8 +103,8 @@ enum {
 
 static struct fbcon_display fb_display[MAX_NR_CONSOLES];
 
-struct fb_info *fbcon_registered_fb[FB_MAX];
-int fbcon_num_registered_fb;
+static struct fb_info *fbcon_registered_fb[FB_MAX];
+static int fbcon_num_registered_fb;
 
 #define fbcon_for_each_registered_fb(i)		\
 	for (i = 0; WARN_CONSOLE_UNLOCKED(), i < FB_MAX; i++)		\