Add the two Interrupt Translation Service (ITS) IPs that are part of the
GIC-600, which are required for message signalled interrupts (MSI). This
is required for PCIe, which fully relies on MSI for interrupts.

Enabling the ITS nodes requires an operating system, that has a
workaround for Rockchip errata #3588001 (GIC600 can not support
shareable attribute).

Co-developed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>