V3U is actually gen4, not gen3. The same IP is also used in the
(not-yet-supported) V4H.

Change VI6_IP_VERSION_MODEL_VSPD_V3U to VI6_IP_VERSION_MODEL_VSPD_GEN4,
to represent the model correctly. V3U and V4H can still be
differentiated, if needed, with the VI6_IP_VERSION_SOC_xxx.

Also mark VI6_IP_VERSION_MODEL_VSPD_GEN4 as gen 4 in vsp1_device_info,
and update the code to correctly match for gen 4.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>