ARM: dts: keystone-k2e: add DT bindings for PCI controller for port 1

K2E SoC has a second PCI port based on Synopsis Designware PCIe h/w.
Add DT bindings to support PCI controller for port 1 for this SoC.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>