riscv: dts: microchip: drop duplicated nodes

The DTSI file defines soc node and address/size cells, so there is no
point in duplicating it in DTS file.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>