ALSA: HDA: Correctly apply position_fix quirks for ATI and VIA controllers

Position_fix quirks for specific machines now override the default
position_fix behavior for all HDA controllers.

BugLink: http://launchpad.net/bugs/465942
BugLink: http://launchpad.net/bugs/580749
BugLink: http://launchpad.net/bugs/587546



Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>