PCI quirk: only apply CX700 PCI bus parking quirk if external VT6212L is present

Apply the CX700 quirk only when an external VT6212L is present (which
is the case for the errant hardware the quirk was written for), don't
touch the settings otherwise -- Hauppage PVR-500 tuners need PCI Bus
Parking in order to work and when that's turned on everything seems
to behave fine.

I guess the underlying problem is a combination of an external VT6212L
and the CX700 rather than the CX700's PCI being broken completely for
all cases...

Reported-by: Jeroen Roos <jeroen@roosnl.com>
Signed-off-by: Tim Yamin <plasm@roo.me.uk>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>