The buck2 output of the PMIC is the VDD core voltage of the cpu.
Switching off this will poweroff the CPU. Add the 'regulator-always-on'
property to avoid this.
Fixes: 8668d8b2e67f ("arm64: dts: Add the Kontron i.MX8M Mini SoMs and
baseboards")
Signed-off-by: Heiko Thiery <heiko.thiery@xxxxxxxxx>