dt-bindings: usb: uac2: Add configuration speed selectors

Every High-Speed capable device must be able to enumerate at Full-Speed.
The functionality at different speeds can be different. Sometimes it is
possible to support exactly the same functionality on both High-Speed
and Full-Speed, but sometimes it is not. The problem is particurarly
relevant for UAC2 because it utilizes isochronous endpoints which means
that the available bandwidth is drastically different between High-Speed
and Full-Speed.

Full-Speed isochronous endpoint can support up to 1023 bytes per frame.
Typical 48 kHz 16-bit stereo stream consumes 48 * 2 * 2 = 192 bytes per
frame. Zephyr UAC2 instances with such streams are fine to work both at
Full-Speed and High-Speed.

An example stream that is too much for Full-Speed is the sometimes used
192 kHz 24-bit stereo (whether or not it is useful is out-of-scope here,
because it should be up to application developer) which would require
192 * 3 * 2 = 1152 bytes per frame.

Because the bandwidth required for audio stream depends on three
different parameters (sample rate, bit resolution and number of
channels), the UAC2 implementation should not automatically limit
available parameters to fit bandwidth requirements.

Adding explicit full-speed and high-speed boolean options to zephyr,uac2
compatible seems to be not only the easiest solution to the problem, but
also the most flexible one. Depending on the use case, the application
developer can then decide for example:
 * to not support High-Speed at all - by having one zephyr,uac2 instance
   with full-speed property
 * to not support Full-Speed at all - by having one zephyr,uac2 instance
   with high-speed property
 * to support limited number of channels at Full-Speed and all channels
   at High-Speed - by having one zephyr,uac2 instance with full-speed
   property and separate instance with high-speed property
 * to have exactly the same functionality at both speeds - by having one
   zephyr,uac2 instance with both full-speed and high-speed properties

(cherry picked from commit 22bde52)

Original-Signed-off-by: Tomasz Moń <tomasz.mon@nordicsemi.no>
GitOrigin-RevId: 22bde52
Cr-Build-Id: 8738238973287044049
Cr-Build-Url: https://cr-buildbucket.appspot.com/build/8738238973287044049
Copybot-Job-Name: zephyr-main-copybot-downstream
Change-Id: Ie0f96b3b0a2f76e24412b0b768d4946c661c633d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5827659
Commit-Queue: Ting Shen <phoenixshen@chromium.org>
Tested-by: Ting Shen <phoenixshen@chromium.org>
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Reviewed-by: Ting Shen <phoenixshen@chromium.org>

dts/bindings/usb/uac2/zephyr,uac2.yaml

@@ -17,6 +17,16 @@ compatible: "zephyr,uac2"
 # "consume" one of the available IDs.
 
 properties:
+ full-speed:
+ type: boolean
+ description: |
+ True if this instance is allowed to operate at Full-Speed.
+
+ high-speed:
+ type: boolean
+ description: |
+ True if this instance is allowed to operate at High-Speed.
+
  audio-function:
  type: int
  required: true