Merge branch 'net-dsa-mv88e6xxx-Peridot-Topaz-SERDES-changes'

Marek Behún says:

====================
net: dsa: mv88e6xxx: Peridot/Topaz SERDES changes

this is the fifth version of changes for the Topaz/Peridot family of
switches. The patches apply on net-next.
Changes since v4:
 - added Reviewed-by and Tested-by tags on first 2 patches, the others
   are changed are affected by changes in patch 3/6, so I did not add
   the tags, except for 5/6, which is just macro renaming
 - patch 3 was changed: the serdes_get_lane returns 0 on success (lane
   was discovered), -ENODEV if not lane is present on the port, and
   other error if other error occured. Lane is put into a pointer of
   type u8
 - patches 4 and 6 were affected by this (error detecting from
   serdes_get_lane)
 - Andrew's complaint about the two additional parameters
   (allow_over_2500 and make_cmode_writable) was addressed, by Vivien's
   advice: I put a new method into chip operations structure, named
   port_set_cmode_writable. This is called from mv88e6xxx_port_setup_mac
   just before port_set_cmode. The method is implemented for Topaz.
   The check if cmodes over 2500 should be allowed on given port is now
   done in the specific port_set_cmode() that requires it, thus the
   allow_over_2500 argument is not needed

Again, tested on Turris Mox with Peridot, Topaz, and Peridot + Topaz.
====================

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