leds: trigger: netdev: Add support for tx_err and rx_err notification with LEDs

leds: trigger: netdev: Add support for tx_err and rx_err notification with LEDs

This patch provides support for enabling blinking of LEDs when RX or TX
errors are detected.

Approach taken in this patch is similar to one for TX or RX data
transmission indication (i.e. TRIGGER_NETDEV_TX/RX attribute).

One can inspect transmission errors with:
ip -s link show eth0

Example LED configuration:
cd /sys/devices/platform/amba_pl@0/a001a000.leds/leds/
echo netdev > mode:blue/trigger && \
echo eth0 > mode:blue/device_name && \
echo 1 > mode:blue/tx_err

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240710100651.4059887-1-lukma@denx.de
Signed-off-by: Lee Jones <lee@kernel.org>