regulator: Add missing platform_set_drvdata in tps6105x_regulator_probe

Otherwise, calling platform_get_drvdata in tps6105x_regulator_remove
returns NULL.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>