Merge branch 'mvneta_qsgmii'

Thomas Petazzoni says:

====================
net: mvneta: fix usage as a module, and support QSGMII properly

This set of patches is a new attempt at fixing the operation of the
mvneta driver when built as a module. For the record, the previous
attempt, merged in commit e3a8786c10e75903f1269474e21fe8cb49c3a670
('net: mvneta: fix usage as a module on RGMII configurations') caused
problems for all RGMII configurations.

In fact, it turned out that the MAC to PHY connection on the Armada XP
GP, which was described as using RGMII-ID according to its Device
Tree, is in fact a QSGMII connection. And the RGMII and QSGMII
configurations have to be handled in a different way in the driver,
because the SERDES configuration is different in those two cases.

So, this patch series fixes that by:

 * Adding minimal handling of a "qsgmii" connection type in the PHY
   layer. Mainly to make sure that a "qsgmii" phy-mode in the Device
   Tree is recognized, and handed over to the driver as
   PHY_INTERFACE_QSGMII.

 * Changing the mvneta driver to properly configure the RGMIIEn and
   PCSEn bits in the GMAC_CTRL_2 register, and configure the SERDES
   register, in the three possible cases: RGMII, SGMII and QSGMII.

 * Updating the Device Tree of the Armada XP GP board to reflect the
   fact that it uses a QSGMII MAC/PHY connection.

PATCH 1 and 2 would be merged by David Miller, through the net tree,
while PATCH 3 would be merged by the mach-mvebu maintainers, through
their tree and arm-soc.

This set of patches has been tested on:

 * Armada XP GP (four QSGMII interfaces)
 * Armada XP DB (two RGMII interfaces and two SGMII interfaces)
 * Armada 370 Mirabox (two RGMII interfaces)

I've tested both the driver built-in, and compiled as a module.

Since the last attempt at fixing this was quite a fiasco, I'd like
this new attempt to be tested more widely before being applied. I'll
try to do some testing on other Armada boards I have, but independent
testing from other persons would also be appreciated.

Note that these patches apply after reverting the previous attempt,
obviously.
====================

Tested-by: Arnaud Ebalard <arno@natisbad.org>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>