RB1: missing usb sound modules for kernel 6.15

[rjtokenring]

Tested on rc7 6.15 kernel build.
Missing snd_usb_audio kernel modules, making not possible to use usb audio gadgets (mic + speakers).
Request is to properly add audio subsistem.

[lool]

@Srinivas-Kandagatla our current images use a mainline kernel built with defconfig + some config fragments; I'll resolve this issue by switching the default builds back to a Debian kernel, but I'd like to carry a config fragment for audio on top of the upstream defconfig, and ideally some smoke tests.

Could you help me with the config fragment, perhaps starting with snd_usb_audio and anything else you deem necessary?

[Srinivas-Kandagatla]

@lool just add CONFIG_SND_USB_AUDIO=m

[rjtokenring]

tested 6.15.3 rebuilt package. USB sound is now working.