arm64: dts: ti: k3-j7200-main: Add PCIe device tree node

Add PCIe device tree node (both RC and EP) for the single PCIe
instance present in j7200.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20210105151421.23237-5-kishon@ti.com