regulator: lp8755: Use devm_regulator_register

This patch moves data allocated using regulator_register to
devm_regulator_register and does away with the calls to
regulator_unregister. Also some labels are removed and a new labelerr is
introduced which is less specific to context.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Mark Brown <broonie@linaro.org>