soc: bcm: brcmstb: pm: pm-arm: Fix refcount leak in brcmstb_pm_probe

In the Linux kernel, the following vulnerability has been resolved: soc: bcm: brcmstb: pm: pm-arm: Fix refcount leak in brcmstb_pm_probe of_find_matching_node() returns a node pointer with refcount incremented, we should use of_node_put() on it when not need anymore. Add missing of_node_put() to avoid refcount leak. In brcmstb_init_sram, it pass dn to of_address_to_resource(), of_address_to_resource() will call of_find_device_by_node() to take reference, so we should release the reference returned by of_find_matching_node().