irqchip/gic-v3: Fix ppi-partitions lookup

irqchip/gic-v3: Fix ppi-partitions lookup

Fix child-node lookup during initialisation, which ended up searching
the whole device tree depth-first starting at the parent rather than
just matching on its children.

To make things worse, the parent gic node was prematurely freed, while
the ppi-partitions node was leaked.

Fixes: e3825ba1af3a ("irqchip/gic-v3: Add support for partitioned PPIs")
Cc: stable <[email protected]>     # 4.7
Signed-off-by: Johan Hovold <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>