drm: return if changed in drm_helper_hpd_irq_event()

The caller may want to know whether the configuration was changed, and
if an hotplug event was sent.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --cc drivers/gpu/drm/drm_crtc_helper.c
Simple merge

diff --cc include/drm/drm_crtc_helper.h
Simple merge