Merge branch 'dpaa2-eth-add-MAC-PHY-support-through-phylink'

Ioana Ciornei says:

====================
dpaa2-eth: add MAC/PHY support through phylink

The dpaa2-eth driver now has support for connecting to its associated PHY
device found through standard OF bindings. The PHY interraction is handled
by PHYLINK and even though, at the moment, only RGMII_* phy modes are
supported by the driver, this is just the first step into adding the
necessary changes to support the entire spectrum of capabilities.

This comes after feedback on the initial DPAA2 MAC RFC submitted here:
https://lwn.net/Articles/791182/

The notable change is that now, the DPMAC is not a separate driver, and
communication between the DPMAC and DPNI no longer happens through
firmware. Rather, the DPMAC is now a set of API functions that other
net_device drivers (DPNI, DPSW, etc) can use for PHY management.

The change is incremental, because the DPAA2 architecture has many modes of
connecting net devices in hardware loopback (for example DPNI to DPNI).
Those operating modes do not have a DPMAC and phylink instance.

The documentation patch provides a more complete view of the software
architecture and the current implementation.

Changes in v2:
 - added patch 1/5 in order to fix module build
 - use -ENOTCONN as a proper return error of dprc_get_connection()
 - move the locks to rtnl outside of dpaa2_eth_[dis]connect_mac functions
 - remove setting supported/advertised from .validate()

Changes in v3:
 - remove an unused variable

Changes in v4:
 - use ERR_PTR instead of plain NULL
====================

Signed-off-by: David S. Miller <davem@davemloft.net>