ARM: dts: BCM53573: Describe Tenda AC9 PCIe card in DT

Tenda AC9 has PCIe controller with just one device connected to it:
0000:00:00.0		14e4:d145	Bridge Device
└─ 0000:01:00.0		14e4:a8db	Network Controller

This card is directly on SoC (doesn't use physical connector) and has
BCM43217 chipset with bcma bus. One of its components is ChipCommon core
which is also a GPIO controller. We need to describe it to be able to
add devices using its GPIO pins.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>