arm64: dts: renesas: hihope-common: Declare pcie bus clock

Declare pcie bus clock, since it is generated on the HiHope RZ/G2M main
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>