usb: gadget: f_uac2: avoid waiting for free operation of sound card

* snd_card_free_when_closed - Disconnect the card, free it later eventually

* Unlike snd_card_free(), this function doesn't try to release the card
* resource immediately, but tries to disconnect at first.  When the card
* is still in use, the function returns before freeing the resources.
* The card resources will be freed when the refcount gets to zero.

This change helps avoid waiting for userspace dependency to close
pcm nodes, which cause adb daemon to get killed and failing in
writing configurations to trigger configfs bind.

Change-Id: I826f57082b5593a5ac2c2f903104ce15d2fd8b69
Signed-off-by: AKASH KUMAR <quic_akakum@quicinc.com>