Documentation: spi-ir-led: fix spelling mistake "balue"->"value"

There is a spelling mistake in:
      Documentation/bindings/leds/irled/spi-ir-led.txt.
Fix it.

Signed-off-by: Mohana Datta Yelugoti <ymdatta.work@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>