The node is taken from the device pointer, which is supplied as a parameter,
hence no need to have a separate parameter for node. Drop redundant node
parameter in samsung_banks_of_node_get().

While at it, drop "of_" part in the samsung_banks_of_node_get() and
samsung_banks_of_node_put() function names to avoid additional churn
in the next changes.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>