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().

Fixes: 0b741b82

 ("soc: bcm: brcmstb: Add support for S2/S3/S5 suspend states (ARM)")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>