This patch converts the resource management in PCI echoaudio drivers
with devres as a clean up.  Each manual resource management is
converted with the corresponding devres helper, the page allocations
are done with the devres helper, and the card object release is
managed now via card->private_free instead of a lowlevel snd_device.
The irq handler is still managed manually because it's re-acquired at
PM suspend/resume.

This should give no user-visible functional changes.

Link: https://lore.kernel.org/r/20210715075941.23332-33-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>