staging: fsl-dpaa2/ethsw: Add Freescale DPAA2 Ethernet Switch driver

Introduce the DPAA2 Ethernet Switch driver, which manages Datapath Switch
(DPSW) objects discovered on the MC bus.

Suggested-by: Alexandru Marginean <alexandru.marginean@nxp.com>
Signed-off-by: Razvan Stefanescu <razvan.stefanescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>