FROMLIST: usb: gadget: f_uac2: Add missing companion descriptor for feedback EP

The f_uac2 function fails to enumerate when connected in SuperSpeed
due to the feedback endpoint missing the companion descriptor.
We can reuse the ss_epin_desc_comp descriptor and append it behind the
ss_epin_fback_desc both in the static definition of the ss_audio_desc
structure as well as its dynamic construction in setup_headers().

Fixes: 24f779da ("usb: gadget: f_uac2/u_audio: add feedback endpoint support")
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Bug: 199044440
Link: https://lore.kernel.org/linux-usb/20210902014317.16775-1-jackp@codeaurora.org/


Change-Id: I0e8d73d69675b649c6b13a48900b391fd5423129
Signed-off-by: Jack Pham <jackp@codeaurora.org>