ALSA: usb-audio: Fix microphone sound on Nexigo webcam.

I own an external usb Webcam, model NexiGo N930AF, which had low mic volume and
inconsistent sound quality. Video works as expected.

(snip)
[  +0.047857] usb 5-1: new high-speed USB device number 2 using xhci_hcd
[  +0.003406] usb 5-1: New USB device found, idVendor=1bcf, idProduct=2283, bcdDevice=12.17
[  +0.000007] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  +0.000004] usb 5-1: Product: NexiGo N930AF FHD Webcam
[  +0.000003] usb 5-1: Manufacturer: SHENZHEN AONI ELECTRONIC CO., LTD
[  +0.000004] usb 5-1: SerialNumber: 20201217011
[  +0.003900] usb 5-1: Found UVC 1.00 device NexiGo N930AF FHD Webcam (1bcf:2283)
[  +0.025726] usb 5-1: 3:1: cannot get usb sound sample rate freq at ep 0x86
[  +0.071482] usb 5-1: 3:2: cannot get usb sound sample rate freq at ep 0x86
[  +0.004679] usb 5-1: 3:3: cannot get usb sound sample rate freq at ep 0x86
[  +0.051607] usb 5-1: Warning! Unlikely big volume range (=4096), cval->res is probably...