ARM: dts: alt: Add SW2 as GPIO keys

SW2 on Alt is connected as on Lager board. So, use the same GPIO
settings.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20210525091512.29119-1-wsa+renesas@sang-engineering.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>