ALSA: au88x0: Fix incorrect device pointer for preallocation

The code change in commit 6974f8ad ("ALSA: pci: Avoid non-standard
macro usage") contained an incorrect conversion, which left the
invalid pointer passed to the allocator for au88x0 driver.  Fix it.

Fixes: 6974f8ad ("ALSA: pci: Avoid non-standard macro usage")
Link: https://lore.kernel.org/r/20191112143243.22216-1-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>