BACKPORT: FROMGIT: 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.
Add a new ss_epin_fback_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")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Link: https://lore.kernel.org/r/20210909174811.12534-2-jackp@codeaurora.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 199044440
Change-Id: I8ae495878f38ec733af4ddf61a3f5d57f5cd5a80
(cherry picked from commit 595091a1
 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git

 usb-linus)
[jackp: Resolved merge conflict in f_uac2.c due to added code in upstream]
Signed-off-by: Jack Pham <jackp@codeaurora.org>