regulator: clear state each invocation of of_regulator_match

of_regulator_match() saves some dynamcially allocated state into the
match table that's passed to it. By implementation and not contract, for
each match table entry, if non-NULL state is already present,
of_regulator_match() will not overwrite it. of_regulator_match() is
typically called each time a regulator is probe()d. This means it is
called with the same match table over and over again if a regulator
triggers deferred probe. This results in stale, kfree()d data being left
in the match table from probe to probe, which causes a variety of crashes
or use of invalid data.

Explicitly free all output state from of_regulator_match() before
generating new results in order to avoid this.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org