ARM: dts: Update BCM47622 DTS file

Fix a few issue in bcm47622.dtsi file:
- Remove unnecessary cpu_on and cpu_off properties from psci node
- Add the missing gic registers and interrupts property to gic node
- Cosmetic changes

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>