Add a check to avoid NULL pointer dereference error when
booted in non-DT mode. While at it also remove the additional
of_node_get which is no longer needed for of_get_child_by_name
and fix the node pointer.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Reported-by: Philippe Rétornaz <philippe.retornaz@epfl.ch> Signed-off-by: Mark Brown <broonie@linaro.org>