driver: net: fsl-mc: Add APIs for DPMAC objects in FLIB

DPMAC object of Management complex controls Physical MAC and MDIO controller.
It provides APIs for MDIO and link state updates. It also provides APIs for
PHY/link configuration.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>