regulator: tps6524x: Remove *rdev[N_REGULATORS] from struct tps6524x

Current code is using devm_regulator_register() so we don't need to store
*rdev for clean up, use a local variable instead.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>