PCIE stub of ABOX IP

This device is an audio subsystem of Exynos AP

Required properties:

- compatible : "samsung,abox-pci"

- memory-region = phandle to reserved memory for PCIE

- reg : <0x0 0x0 0x0>.

- pinctrl-names : "pci_on", "sleep"

- pinctrl-0 : phandle to pinctrl for pci on

- pinctrl-1 : phandle to pinctrl for pci off

- s2mpu_mailbox : address of mailbox

Optional properties: no optional property.