ALSA: hda: fix unused variable warning

When CONFIG_X86=n function azx_snoop doesn't use the variable chip it
only returns true.

sound/pci/hda/hda_intel.c: In function ‘dma_alloc_pages’:
sound/pci/hda/hda_intel.c:2002:14: warning: unused variable ‘chip’ [-Wunused-variable]
  struct azx *chip = bus_to_azx(bus);
              ^~~~

Create a inline function of azx_snoop.

Fixes: a41d1224 ("ALSA: hda - Embed bus into controller object")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>