arm64: dts: ls1012a: Add MSI controller DT node

Add MSI controller node for ls1012a platform.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Minghuan Lian <minghuan.Lian@nxp.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>