x86/PCI: fixup early quirk probing

On x86, we do early PCI probing to apply some quirks for chipset bugs.
However, in a recent cleanup (7bcbc78dea92fdf0947fa48e248da3c993a5690f) a
thinko was introduced that causes us to probe all subfunctions of even single
function devices (a function was factored out of an inner loop and a "break"
became a "return").  Fix that up by making check_dev_quirk() return a value so
we can keep the factored code intact.

Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>