drivers: net: Add Felix DSA switch driver

This driver is used for the Ethernet switch integrated into LS1028A NXP.
Felix on LS1028A has 4 front panel ports and two internal ports, I/O
to/from the switch is done through an ENETC Ethernet interface.
The 4 front panel ports are available as Ethernet interfaces and can be
used with the typical network commands like tftp.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>