ATI and AMD chipsets seem not providing the proper position-buffer
information, and it also doesn't provide FIFO register required by
VIACOMBO fix.  It's better to use LPIB for these.
Reported-by: David Henningsson <david.henningsson@canonical.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>