Refactor nested mdiobus read/write functions

In order to avoid locked signal false positive for nested mdiobus read/write calls, nested code was introduced in mv88e6xxx and mdio-mux.
But mv88e6060 also needs such nested mdiobus read/write calls. For sake of refactoring, introduce nested variants of mdiobus read/write and make them used by mv88e6xxx and mv88e6060.
In a next patch, mdio-mux should also use these variant calls.

Neil Armstrong (3):
net: phy: Add nested variants of mdiobus read/write
net: dsa: Make mv88e6xxx use nested mdiobus read/write
net: dsa: Make mv88e6060 use nested mdiobus read/write

 drivers/net/dsa/mv88e6060.c |  4 ++--
 drivers/net/dsa/mv88e6xxx.c | 46 ++++++++-----------------------------
 drivers/net/phy/mdio_bus.c  | 55 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/phy.h         |  2 ++
 4 files changed, 68 insertions(+), 39 deletions(-)

In order to avoid locked signal false positive for nested mdiobus read/write calls, nested code was introduced in mv88e6xxx and mdio-mux.
But mv88e6060 also needs such nested mdiobus read/write calls. For sake of refactoring, introduce nested variants of mdiobus read/write and make them used by mv88e6xxx and mv88e6060.
In a next patch, mdio-mux should also use these variant calls.