regulator: core: Add of_node_get to of_regulator_match

Currently, of_regulator_match does not increment the reference count of
the of_nodes it takes new references to. This could cause the node
pointer held to be invalid, by the time it is passed to the regulator
core. This patchs adds an of_node_get when we copy each of_node pointer
into the match structure.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>