PCI subsystem has support for drivers limiting the number of VFs
available below what the IOV capability claims. Make use of it.
While at it remove the #ifdef/#endif on CONFIG_PCI_IOV, it was
there to avoid unnecessary warnings in case device read failed
but kernel doesn't have SR-IOV support anyway. Device reads
should not fail.
Note that we still need the driver-internal check for the case
where max VFs is 0 since PCI subsystem treats 0 as limit not set.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>