Fix ixl(4) compilation with PCI_IOV pre-r266974

stable/10 doesn't have the if_getdrvflags(9) KPI. Reference the field in the
structure directly if the __FreeBSD_version is < 1100022, so the driver can
be built with PCI_IOV support on stable/10, without backporting all of
r266974 (which requires additional changes due to projects/ifnet, etc)

Differential Revision: https://reviews.freebsd.org/D4759
Reviewed by: erj, sbruno
Sponsored by: EMC / Isilon Storage Division

sys/dev/ixl/if_ixl.c

@@ -6606,7 +6606,11 @@ ixl_iov_uninit(device_t dev)
 		pf->veb_seid = 0;
 	}
 
+#if __FreeBSD_version > 1100022
 	if ((if_getdrvflags(ifp) & IFF_DRV_RUNNING) == 0)
+#else
+	if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0)
+#endif
 		ixl_disable_intr(vsi);
 
 	vfs = pf->vfs;