fbcon: Add necessary include statements and forward declarations

Make the header self contained for including.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20250715122643.137027-6-tzimmermann@suse.de

include/linux/fbcon.h

@@ -1,6 +1,13 @@
 #ifndef _LINUX_FBCON_H
 #define _LINUX_FBCON_H
 
+#include <linux/compiler_types.h>
+
+struct fb_blit_caps;
+struct fb_info;
+struct fb_var_screeninfo;
+struct fb_videomode;
+
 #ifdef CONFIG_FRAMEBUFFER_CONSOLE
 void __init fb_console_init(void);
 void __exit fb_console_exit(void);