nfp: reorder SR-IOV config and nfp_app SR-IOV callbacks

We previously assumed that app callback can be guaranteed to be
executed before SR-IOV is actually enabled.  Given that we can't
guarantee that SR-IOV will be disabled during probe or that we
will be able to disable it on remove, we should reorder the callbacks.
We should also call the app's sriov_enable if SR-IOV was enabled
during probe.

Application FW must be able to disable VFs internally and not depend
on them being removed at PCIe level.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>