arm64: dts: broadcom: Add reference to Raspberry Pi 3 B+

This adds a reference to the dts of the Raspberry Pi 3 B+
in arm, so don't need to maintain the content in arm64.
Signed-off-by: NStefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NEric Anholt <eric@anholt.net>

arch/arm64/boot/dts/broadcom/Makefile

 # SPDX-License-Identifier: GPL-2.0
-dtb-$(CONFIG_ARCH_BCM2835) += bcm2837-rpi-3-b.dtb
+dtb-$(CONFIG_ARCH_BCM2835) += bcm2837-rpi-3-b.dtb \
+			      bcm2837-rpi-3-b-plus.dtb
 
 subdir-y	+= northstar2
 subdir-y	+= stingray

arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b-plus.dts

+// SPDX-License-Identifier: GPL-2.0
+#include "arm/bcm2837-rpi-3-b-plus.dts"