Rename the `dvfs_ops` and `pmic_ops` members of `struct acpm_ops` to
`dvfs` and `pmic` respectively.
Since these members are housed within the `acpm_ops` structure and
utilize the `acpm_*_ops` types, the `_ops` suffix on the variable names
creates unnecessary redundancy (e.g., `handle.ops.dvfs_ops`).
This cleanup removes the stuttering, leading to cleaner consumer code.