ARM: omap1: Fix up the Retu IRQ on Nokia 770

The Retu IRQ is off by one, as a result the power button does not work.
Fix it.

Fixes: 084b6f21 ("ARM: omap1: Fix up the Nokia 770 board device IRQs")
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/Z3UxH_fOzuftjnuX@darkstar.musicnaut.iki.fi


Signed-off-by: Kevin Hilman <khilman@baylibre.com>