drm/fb-helper: Remove struct drm_fb_helper.fb_probe

drm/fb-helper: Remove struct drm_fb_helper.fb_probe

The callback fb_probe in struct drm_fb_helper is unused. Remove it.
New drivers should set struct drm_driver.fbdev_probe instead and call
drm_client_setup() to instantiate in-kernel DRM clients.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241212170913.185939-13-tzimmermann@suse.de
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>