sky2: Disable MSI on yet another ASUS boards (P6Xxxx)

A similar workaround for the suspend/resume problem is needed for yet
another ASUS machines, P6X models.  Like the previous fix, the BIOS
doesn't provide the standard DMI_SYS_* entry, so again DMI_BOARD_*
entries are used instead.

Reported-and-tested-by: SteveM <swm@swm1.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>