arm64: dts: broadcom: northstar2: Drop GIC V2M "interrupt-parent"

arm64: dts: broadcom: northstar2: Drop GIC V2M "interrupt-parent"

The default interrupt parent is a parent node containing
"#interrupt-cells", so an explicit "interrupt-parent" is not necessary.

Fixes these dtschema warnings:

(arm,gic-400): v2m@70000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@60000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@50000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@40000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@30000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@20000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@10000: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'
(arm,gic-400): v2m@0: 'interrupt-parent' does not match any of the regexes: '^pinctrl-[0-9]+$'

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250609203705.2852500-1-robh@kernel.org
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>