leds: trigger: gpio: Use GPIOD_FLAGS_BIT_NONEXCLUSIVE

leds: trigger: gpio: Use GPIOD_FLAGS_BIT_NONEXCLUSIVE

When a GPIO is shared between the LED trigger driver and another driver,
the LED trigger driver needs to request the GPIO with
GPIOD_FLAGS_BIT_NONEXCLUSIVE to allow both drivers to monitor the same
GPIO pin.

Without this flag, if another driver has already claimed the GPIO,
the LED trigger driver's gpiod_get_optional() call fails silently,
and the LED trigger doesn't work.

This is needed for scenarios like:
- SFP module presence/status LED triggered by SFP Mod_ABS/Rx_LOS

Both GPIOs are also monitored by the SFP driver for module state
management, so they need to be shared.

Signed-off-by: Piotr Kubik <piotr@kubik.pl>
Link: https://patch.msgid.link/20260408115106.379834-1-piotr@kubik.pl
Signed-off-by: Lee Jones <lee@kernel.org>