net: ti: icssg: Add support sending FDB command to update rx_flow_id

ICSSG firmware supports FDB commands. Add support to send FDB commands
from driver. Once rx_flow_id is obtained from dma, let firmware know that
we are using this rx_flow_id by sending a FDB command.

Reviewed-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>

net: ti: icssg: Add Firmware config and classification APIs.

Add icssg_config.h / .c and icssg_classifier.c files. These are firmware
configuration and classification related files. Add MII helper APIs and
MACROs. These APIs and MACROs will be later used by ICSSG Ethernet driver.
Also introduce icssg_prueth.h which has definition of prueth related
structures.

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Reviewed-by: Ravi Gunasekaran <r-gunasekaran@ti.com>