regulator: tps65910: use of_node of matched regulator being register

After getting matched regulators by using of_regulator_match(),
initialize the config.of_node of regulator being register with
of_regulator_match.of_node of that regulator.
This is require for supporting regulator consumers in dt.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>