of_pci_get_host_bridge_resources() allocates the resource structures it
fills dynamically, but none of its callers care to release them so far.
Rather than requiring everyone to do this explicitly, convert the existing
function to a managed version.

Tested-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Acked-by: Joao Pinto <jpinto@synopsys.com>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>