ARM: dts: rockchip: rock5b: enable pcie2x1l2 and associated combphy

Enable the PCIe 2x1l 2 device and associated combphy.
On this bus, the Rock5B has an Ethernet transceiver connected.

Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>
[eugen.hristev@collabora.com: minor tweaks]
Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com>
[jonas@kwiboo.se: add PCIe pins]
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>