i40evf: enable bus master after reset

BugLink: http://bugs.launchpad.net/bugs/1547674

If the VF is reset via VFLR, the device will be knocked out of bus
master mode, and the driver will fail to recover from the reset. Fix
this by enabling bus mastering after every reset. In a non-VFLR case,
the bus master bit will not be disabled, and this call will have no effect.

Change-ID: Id515859ac7a691db478222228add6d149e96801a
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from net-next commit 509a447a)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/net/ethernet/intel/i40evf/i40evf_main.c

@@ -1837,6 +1837,7 @@ static void i40evf_reset_task(struct work_struct *work)
 			break;
 		msleep(I40EVF_RESET_WAIT_MS);
 	}
+	pci_set_master(adapter->pdev);
 	/* extra wait to make sure minimum wait is met */
 	msleep(I40EVF_RESET_WAIT_MS);
 	if (i == I40EVF_RESET_WAIT_COUNT) {