ARM: dts: ux500: samsung-skomer: Add magnetometer

Add the ALPS magnetometer to the Skomer phone.

Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: Nick Reitemeyer <nick.reitemeyer@web.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20200430150245.7935-2-linus.walleij@linaro.org