pfuze100-regulator: Fix of_node_get() parameter

Since commit d7857c42 (regulator: pfuze100: Use of_get_child_by_name) we get
the following probe failure:

pfuze100-regulator 1-0008: Full layer: 1, Metal layer: 0
pfuze100-regulator 1-0008: FAB: 0, FIN: 0
pfuze100-regulator 1-0008: regulators node not found
pfuze100-regulator: probe of 1-0008 failed with error -22

Now that of_get_child_by_name() is used we should adjust the device_node pointer
'np' to not get the parent node anymore.

Suggested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>