drivers: usb: lan78xx: add support to control LED mode register

[teslafields]

I am not really sure if this is the right place to suggest this contribution, but I don't know where else to do it.

Currently, the lan78xx driver is checking if "microchip,led-modes" property was set in the devicetree, then it only enables the LEDs by writing to the HW_CFG register. This however is not enough, as the property, when set, contains the value of each defined LED, and so it's necessary to read these values and write to the PHY LED Mode register accordingly.

Following the documentation (Documentation/devicetree/bindings/net/microchip,lan78xx.txt):

Optional properties of the embedded PHY:
- microchip,led-modes: a 0..4 element vector, with each element configuring
  the operating mode of an LED. Omitted LEDs are turned off. Allowed values
  are defined in "include/dt-bindings/net/microchip-lan78xx.h".

[LeSpocky]

I am not really sure if this is the right place to suggest this contribution, but I don't know where else to do it.

Your changes only touch things in drivers/net so I'm pretty sure this is stuff for the netdev mailing list. See these pages in the Linux kernel documentation:

• https://docs.kernel.org/process/maintainer-netdev.html
• https://docs.kernel.org/process/submitting-patches.html