VBLANK callbacks in struct drm_driver are deprecated in favor of
their equivalents in struct drm_crtc_funcs. Convert vc4 over.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123135943.24140-19-tzimmermann@suse.de