add DM/DTS support for the UEC ethernet on QUICC Engine
Block.

Signed-off-by: Heiko Schocher <hs@denx.de>
Patch-cc: Mario Six <mario.six@gdsys.cc>
Patch-cc: Qiang Zhao <qiang.zhao@nxp.com>
Patch-cc: Holger Brunck <holger.brunck@hitachi-powergrids.com>
Patch-cc: Madalin Bucur <madalin.bucur@oss.nxp.com>

Series-changes: 3
- revert:
  commit "3374264df97b" ("drivers: net: qe: deselect QE when DM_ETH is enabled")
  as now qe works with DM and DM_ETH support.
- fix mailaddress from Holger

Series-changes: 2
- add comments from Qiang Zhao:
  - add device node documentation
  - I did not drop the dm_qe_uec_phy.c and use drivers/net/fsl_mdio.c
    because using drivers/net/fsl_mdio.c leads in none existent
    udevice mdio@3320
    instead boards with DM ETH support should use now this
    driver.
- remove RFC tag

Commit-notes:

- I let the old none DM based implementation in code
  so boards should work with old implementation.
  This Code should be removed if all boards are converted
  to DM/DTS.

- add the DM based qe uec driver under drivers/net/qe

- Therefore copied the files uccf.c uccf.h uec.h from
  drivers/qe. So there are a lot of Codingstyle problems
  currently. I fix them in next version if this RFC
  patch is OK or it needs some changes.

- The dm based driver code is now under drivers/net/qe/dm_qe_uec.c
  Used a lot of functions from drivers/qe/uec.c

- seperated the PHY specific code into seperate file
  drivers/net/qe/dm_qe_uec_phy.c

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