regulator: gpio: Fix some error handling paths in 'gpio_regulator_probe()'

Re-order error handling code and gotos to avoid leaks in error handling
paths.

Fixes: 9f946099 ("regulator: gpio: fix parsing of gpio list")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>