soc: bcm: brcmstb: biuctrl: Add missing of_node_put()

In brcmstb_biuctrl_init(), of_find_compatible_node() will return a
node pointer with refcount incremented. We should use of_node_put()
in each fail path or when it is not used anymore.

Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>