ARM: boot: dts: bcm2711: Add BCM2711 VEC compatible

The BCM2711 has a slightly different VEC than the one found in the older
SoCs. Now that we support the new variant, add its compatible to the
device tree.

Signed-off-by: Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210520150344.273900-5-maxime@cerno.tech
Signed-off-by: Nicolas Saenz Julienne <nsaenz@kernel.org>