fbdev: Read video= option with fb_get_option() in modedb

Get the kernel's global video= parameter with fb_get_option(). Done
to unexport the internal fbdev state fb_mode_config. No functional
changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230209135509.7786-6-tzimmermann@suse.de

drivers/video/fbdev/core/modedb.c

@@ -620,6 +620,7 @@ int fb_find_mode(struct fb_var_screeninfo *var,
 		 const struct fb_videomode *default_mode,
 		 unsigned int default_bpp)
 {
+	char *mode_option_buf = NULL;
 	int i;
 
 	/* Set up defaults */
@@ -635,8 +636,10 @@ int fb_find_mode(struct fb_var_screeninfo *var,
 		default_bpp = 8;
 
 	/* Did the user specify a video mode? */
-	if (!mode_option)
-		mode_option = fb_mode_option;
+	if (!mode_option) {
+		fb_get_options(NULL, &mode_option_buf);
+		mode_option = mode_option_buf;
+	}
 	if (mode_option) {
 		const char *name = mode_option;
 		unsigned int namelen = strlen(name);
@@ -715,6 +718,7 @@ int fb_find_mode(struct fb_var_screeninfo *var,
 			res_specified = 1;
 		}
 done:
+		kfree(mode_option_buf);
 		if (cvt) {
 			struct fb_videomode cvt_mode;
 			int ret;