ALSA: hda - Replace ICH6_ prefix

ICH6_ prefix doesn't mean that it's specific to ICH6 chipset but
rather its generic for all HD-audio (or "Azalia") devices.
Use AZX_ prefix instead to align with other constants.

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

diff --cc sound/pci/hda/hda_controller.c
Simple merge

diff --cc sound/pci/hda/hda_intel.c
Simple merge

diff --cc sound/pci/hda/hda_priv.h
Simple merge