phy: core: rework phy_set_mode to accept phy mode and submode

phy: core: rework phy_set_mode to accept phy mode and submode

Currently the attempt to add support for Ethernet interface mode PHY
(MII/GMII/RGMII) will lead to the necessity of extending enum phy_mode and
duplicate there values from phy_interface_t enum (or introduce more PHY
callbacks) [1]. Both approaches are ineffective and would lead to fast
bloating of enum phy_mode or struct phy_ops in the process of adding more
PHYs for different subsystems which will make them unmaintainable.

As discussed in [1] the solution could be to introduce dual level PHYs mode
configuration - PHY mode and PHY submode. The PHY mode will define generic
PHY type (subsystem - PCIE/ETHERNET/USB_) while the PHY submode - subsystem
specific interface mode. The last is usually already defined in
corresponding subsystem headers (phy_interface_t for Ethernet, enum
usb_device_speed for USB).

This patch is cumulative change which refactors PHY framework code to
support dual level PHYs mode configuration - PHY mode and PHY submode. It
extends .set_mode() callback to support additional parameter "int submode"
and converts all corresponding PHY drivers to support new .set_mode()
callback declaration.
The new extended PHY API
 int phy_set_mode_ext(struct phy *phy, enum phy_mode mode, int submode)
is introduced to support dual level PHYs mode configuration and existing
phy_set_mode() API is converted to macros, so PHY framework consumers do
not need to be changed (~21 matches).

[1] http://lkml.kernel.org/r/d63588f6-9ab0-848a-5ad4-8073143bd95d@ti.com
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>