regulator: max20086: fix error code in max20086_parse_regulators_dt()

This code accidentally returns PTR_ERR(NULL) which is success.  It
should return a negative error code.

Fixes: bfff546a ("regulator: Add MAX20086-MAX20089 driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20220111072657.GK11243@kili


Signed-off-by: Mark Brown <broonie@kernel.org>