iavf: restore MSI state on reset

commit 7e4dcc13 upstream.

If the PF experiences an FLR, the VF's MSI and MSI-X configuration will
be conveniently and silently removed in the process. When this happens,
reset recovery will appear to complete normally but no traffic will
pass. The netdev watchdog will helpfully notify everyone of this issue.

To prevent such public embarrassment, restore MSI configuration at every
reset. For normal resets, this will do no harm, but for VF resets
resulting from a PF FLR, this will keep the VF working.

Fixes: 5eae00c5 ("i40evf: main driver core")
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: George Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>