regmap: Fix memory leak in regcache_hw_init error path

Make sure reg_defaults_raw gets freed in case of an error.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>