net: phy: dp83822: Add support for PHY LEDs on DP83822

net: phy: dp83822: Add support for PHY LEDs on DP83822

The DP83822 supports up to three configurable Light Emitting Diode (LED)
pins: LED_0, LED_1 (GPIO1), COL (GPIO2) and RX_D3 (GPIO3). Several
functions can be multiplexed onto the LEDs for different modes of
operation. LED_0 and COL (GPIO2) use the MLED function. MLED can be routed
to only one of these two pins at a time. Add minimal LED controller driver
supporting the most common uses with the 'netdev' trigger.

Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250107-dp83822-leds-v2-1-5b260aad874f@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>