pci-skeleton: Misc fixes to build neatly

The pci-skeleton.c has several problems with compilation, such as missing args
when calling synchronize_irq(). Fix it.

Signed-off-by: Jike Song <albcamus@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>