leds: led-class-flash:: Fix flash_timeout comment

The comment for the flash_timeout setter mentioned it is the "flash
duration". Fix this by changing it to "flash timeout".

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
Link: https://lore.kernel.org/r/20250617-ov9282-flash-strobe-v5-3-9762da74d065@linux.dev


Signed-off-by: Lee Jones <lee@kernel.org>