fbdev: imxfb: Replace check_fb in favor of struct fb_info.lcd_dev

Store the lcd device in struct fb_info.lcd_dev. The lcd subsystem can
now detect the lcd's fbdev device from this field.

This makes the implementation of check_fb in imxfb_lcd_ops obsolete.
Remove it.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20240906075439.98476-23-tzimmermann@suse.de


Signed-off-by: Lee Jones <lee@kernel.org>