drm/vc4: crtc: Add BCM2711 pixelvalves

The BCM2711 has 5 pixelvalves, so now that our driver is ready, let's add
support for them.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/2553ec9ece0d8a0e5299ff74ed932a38703c5db9.1599120059.git-series.maxime@cerno.tech