leds: trigger: netdev: Configure LED blink interval for HW offload

leds: trigger: netdev: Configure LED blink interval for HW offload

In case a PHY LED implements .blink_set callback to set LED blink
interval, call it even if .hw_control is already set, as that LED
blink interval likely controls the blink rate of that HW offloaded
LED. For PHY LEDs, that can be their activity blinking interval.

The software blinking is not affected by this change.

With this change, the LED interval setting looks something like this:
$ echo netdev > /sys/class/leds/led:green:lan/trigger
$ echo 1 > /sys/class/leds/led:green:lan/brightness
$ echo 250 > /sys/class/leds/led:green:lan/interval

Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20250120113740.91807-1-marex@denx.de
Signed-off-by: Lee Jones <lee@kernel.org>