bebob: rename avc_generic_set/get_sampling_rate

Renaming to the equivalent function in 'AV/C Digital Interface Command Set
General Specification Version 4.2'.
bebob: add device specific operations for Terratek devices

For these devices below:
- Phase 24 FW
- Phase X24 FW
- Phase 88 Rack FW

These devices can switch clock source. But I cannot find the way to check sync.
So change control interface.