arm64: dts: broadcom: rp1: drop RP1 overlay

RP1 support loaded from overlay has been dropped from the driver and
the DTB intended to be loaded with the overlay no longer exists.

Drop unused include file and overlay.

Signed-off-by: Andrea della Porta <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/8516[e-mail]
Signed-off-by: Florian Fainelli <[e-mail]>

arch/arm64/boot/dts/broadcom/Makefile

···
 			      bcm2837-rpi-3-b.dtb \
 			      bcm2837-rpi-3-b-plus.dtb \
 			      bcm2837-rpi-cm3-io3.dtb \
-			      bcm2837-rpi-zero-2-w.dtb \
-			      rp1.dtbo
+			      bcm2837-rpi-zero-2-w.dtb
 
 subdir-y	+= bcmbca
 subdir-y	+= northstar2

arch/arm64/boot/dts/broadcom/rp1-nexus.dtsi

···
-// SPDX-License-Identifier: (GPL-2.0 OR MIT)
-
-rp1_nexus {
-	compatible = "pci1de4,1";
-	#address-cells = <3>;
-	#size-cells = <2>;
-	ranges = <0x01 0x00 0x00000000
-		  0x02000000 0x00 0x00000000
-		  0x0 0x400000>;
-	interrupt-controller;
-	#interrupt-cells = <2>;
-
-	#include "rp1-common.dtsi"
-};

arch/arm64/boot/dts/broadcom/rp1.dtso

···
-// SPDX-License-Identifier: (GPL-2.0 OR MIT)
-
-/dts-v1/;
-/plugin/;
-
-&pcie2 {
-	#address-cells = <3>;
-	#size-cells = <2>;
-
-	#include "rp1-nexus.dtsi"
-};