regulator: da9121: Potential Oops in da9121_assign_chip_model()

There is a missing "return ret;" on this error path so we call
"da9121_check_device_type(i2c, chip);" which will end up dereferencing
"chip->regmap" and lead to an Oops.

Fixes: c860476b ("regulator: da9121: Add device variant regmaps")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Adam Ward <Adam.Ward.opensource@diasemi.com>
Link: https://lore.kernel.org/r/X85soGKnWAjPUA7a@mwanda


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