arm64: dts: broadcom: Add reference to RPi 4 B

This adds a reference to the dts of the Raspberry Pi 4 B,
so we don't need to maintain the content in arm64.
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>

arch/arm64/boot/dts/broadcom/Makefile

 # SPDX-License-Identifier: GPL-2.0
-dtb-$(CONFIG_ARCH_BCM2835) += bcm2837-rpi-3-a-plus.dtb \
+dtb-$(CONFIG_ARCH_BCM2835) += bcm2711-rpi-4-b.dtb \
+			      bcm2837-rpi-3-a-plus.dtb \
 			      bcm2837-rpi-3-b.dtb \
 			      bcm2837-rpi-3-b-plus.dtb \
 			      bcm2837-rpi-cm3-io3.dtb

arch/arm64/boot/dts/broadcom/bcm2711-rpi-4-b.dts

+// SPDX-License-Identifier: GPL-2.0
+#include "arm/bcm2711-rpi-4-b.dts"