backlight: wm831x_bl: Do not include <linux/fb.h>

This driver does not require <linux/fb.h>. Remove the include
statement.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250131140103.278158-17-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>

Author: tdz

drivers/video/backlight/wm831x_bl.c

@@ -9,7 +9,6 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/module.h>
-#include <linux/fb.h>
 #include <linux/backlight.h>
 #include <linux/slab.h>