src/meta-raspberrypi:rpi-base: Remove bcm2712-rpi-5-b.dtb from RPI_KE…

…RNEL_DEVICETREE target

All bcm2712 are built for arm64 builds alone and rpi-base.inc is included
by 32-bit machine configs as well. Recently, kernel moved thesr dts files
into arch/arm64/boot/dts/broadcom/ folder [1]

[1] raspberrypi/linux@10c77e1

Signed-off-by: Khem Raj <raj.khemgmail.com>