ALSA: usb-audio: Properly refcounting clock rate

[ Upstream commit 9a737e7f ]

We fixed the bug introduced by the patch for managing the shared
clocks at the commit 809f44a0 ("ALSA: usb-audio: Clear fixed clock
rate at closing EP"), but it was merely a workaround.  By this change,
the clock reference rate is cleared at each EP close, hence the still
remaining EP may need a re-setup of rate unnecessarily.

This patch introduces the proper refcounting for the clock reference
object so that the clock setup is done only when needed.

Fixes: 809f44a0 ("ALSA: usb-audio: Clear fixed clock rate at closing EP")
Fixes: c11117b6

 ("ALSA: usb-audio: Refcount multiple accesses on the single clock")
Link: https://lore.kernel.org/r/20220920181126.4912-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Stable-dep-of: 7822baa8

 ("ALSA: usb-audio: add quirk for RODE NT-USB+")
Signed-off-by: Sasha Levin <sashal@kernel.org>