arm64: dts: renesas: hihope-rzg2-ex: Enable PCIe support

This patch enables PCIEC[01] PCI express controller on the sub board.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>