hal: Fix strncat problem, replace with strlcat

- 3rd parameter in strncat is not calculated properly. Replace with
strlcat() and fix the concatenation.
- Rename mixer control name to clarify where it applies.

Change-Id: I70af10190aaaf63b2a7d7e16a96ecda603b163dd
CRs-fixed: 811371
2 files changed