arm64: dts: renesas: r8a77990: sort pciec0 node within soc node

Move the pciec0 node so that sub-nodes of the soc node are
sorted by bus address.

This change has no run-time affect.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>