mfd: cros_ec: Simplify and clean-up cros_ec_dev_init()

Simplify cros_ec_dev_init() by the following changes:
- Get rid of label `failed_devreg`.
- Remove a redundant space and comment.
- Use `if (ret)` instead of `if (ret < 0)`.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20240819102326.5235-1-tzungbi@kernel.org


Signed-off-by: Lee Jones <lee@kernel.org>