From: Jake Moilanen <moilanen@austin.ibm.com>

On a ppc64 logically partitioned system, there can be a setup where function
0 of a PCI-PCI bridge is assigned to one partition and (for example) function
2 is assigned to a second partition.  On the second partition, it would
appear that function 0 does not exist, but function 2 does.  If all the
functions are not scanned, everything under function 2 would not be detected.

This patch allows devices that don't respond to function 0, but do respond to
other functions to be marked with a quirk and have all of their functions
scanned.