drm/vc4: Reorder the bind order of the devices

We'll need the HVS to be bound before the TXP for the upcoming reworks, but
it needs to happen before the PV are bound so that the code to set the
possible_crtcs field works properly on the TXP. Move it right between the
two devices.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/2d7fcde29dec429442eb76afc51d8cc275cb407f.1591882579.git-series.maxime@cerno.tech