arm64: dts: ti: k3-j721e-common-proc-board: Configure the PCIe instances

J721E Common Processor Board has PCIe connectors for the 1st three PCIe
instances. Configure the three PCIe instances in RC mode and disable the
4th PCIe instance.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20200914152115.1788-3-kishon@ti.com