ARM: dts: ux500-golden: Add proper supplies to touchscreen

This sets up the Atmel maXTouch touchscreen to use proper
VDDA and VDD supplies as now supported by bindings and
driver.

Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: Nick Reitemeyer <nick.reitemeyer@web.de>
Cc: Nick Dyer <nick@shmanahar.org>
Link: https://lore.kernel.org/r/20201120124212.1086063-1-linus.walleij@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>