PCI: Run k8t_sound_hostbridge quirk only when needed

The k8t_sound_hostbridge PCI quick fires on my motherboard (Jetway
K8M8MS) while it shouldn't: the on-board sound chip is not disabled
and is working just fine. Looking at the code, I see that we are
running the quirk for two distinct register values (0x88 and 0xc8)
and then clear bit 6 (0x40). However value 0x88 already has bit 6
cleared so this is a no-op. This is what happens on my board. Thus I
believe that the quirk should only be run for register value 0xc8.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>