The sample rate selection of snd_uaudio(4) at runtime was implicitly
relying on a specific order in the device config list. In case a default
was set through the hw.usb.uaudio.default_rate sysctl tunable, commit
42fdcd9fd917 removed a duplicate sample rate entry from that list, which
inadvertently broke sample rate selection at runtime.
Implement sample rate selection in a more robust way.
Reported by: Lexi Winter <lexi@le-fay.org>