Replace the call to drm_fb_helper_output_poll_changed() with a call
to drm_client_dev_hotplug(). It is equivalent in functionality, but
uses the DRM client infrastructure.

v2:
- fix commit description
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240812083000.337744-6-tzimmermann@suse.de