ARM64: dts: bcm: Use a symlink to R-Pi dtsi files from arch=arm

ARM64: dts: bcm: Use a symlink to R-Pi dtsi files from arch=arm

The ../../../arm... style cross-references added by commit 9d56c22a7861
("ARM: bcm2835: Add devicetree for the Raspberry Pi 3.") do not work in the
context of the split device-tree repository[0] (where the directory
structure differs). As with commit 8ee57b8182c4 ("ARM64: dts: vexpress: Use
a symlink to vexpress-v2m-rs1.dtsi from arch=arm") use symlinks instead.

[0] https://git.kernel.org/cgit/linux/kernel/git/devicetree/devicetree-rebasing.git/

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Lee Jones <lee@kernel.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-rpi-kernel@lists.infradead.org
Cc: arm@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>