Auto-assigned-address pci function (passing devfn = -1) is always
single function.
This patch adds assert() to guarantee that auto-assigned-address function
is always single function device at function = 0.
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>