drm/vc4: Add missing formats to vc4_format_mod_supported().

Daniel's format_mod_supported() patch predated Dave's for NV21/61, and
I didn't catch that when rebasing.  This is a problem since the
formats are now getting validated before being passed to the driver's
atomic hooks.

Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Daniel Stone <daniels@collabora.com>
Cc: Dave Stevenson <dave.stevenson@raspberrypi.org>
Fixes: 423ad7b3 ("drm/vc4: Advertise supported modifiers for planes")
Link: https://patchwork.freedesktop.org/patch/msgid/20180316220435.31416-2-eric@anholt.net
(cherry picked from commit 1e871d65)