drm/vc4: hdmi: Remove unused struct

Commitc7d30623540b ("drm/vc4: hdmi: Remove unused struct") removed the
references to the vc4_hdmi_audio_widgets and vc4_hdmi_audio_routes
structures, but not the structures themselves resulting in two warnings.
Remove it.

Fixes: c7d30623 ("drm/vc4: hdmi: Remove unused struct")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210819140753.930751-1-maxime@cerno.tech


Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>