arm64: dts: zii-ultra: fix ARM regulator states

The GPIO controlled regulator for the ARM power supply is supplying
the higher voltage when the GPIO is driven high. This is opposite to
the similar regulator setup on the EVK board and is impacting stability
of the board as the ARM domain has been supplied with a too low voltage
when to faster OPPs are in use.

Fixes: 4a13b3be (arm64: dts: imx: add Zii Ultra board support)
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>