drm/meson: add Amlogic Video FBC registers

Add the registers of the VPU VD1 Amlogic FBC decoder module, and routing
register.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703080728.25207-3-narmstrong@baylibre.com