rtnetlink: fix rtnl_vfinfo_size

rtnetlink: fix rtnl_vfinfo_size

The size reported by rtnl_vfinfo_size doesn't match the space used by
rtnl_fill_vfinfo.

rtnl_vfinfo_size currently doesn't account for the nest attributes
used by statistics (added in commit 3b766cd83232), nor for struct
ifla_vf_tx_rate (since commit ed616689a3d9, which added ifla_vf_rate
to the dump without removing ifla_vf_tx_rate, but replaced
ifla_vf_tx_rate with ifla_vf_rate in the size computation).

Fixes: ed616689a3d9 ("net-next:v4: Add support to configure SR-IOV VF minimum and maximum Tx rate through ip tool")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Orabug: 27998927

(cherry picked from commit 7e75f74a171a8146cc3ee92d5562878b40c25fb5)
Signed-off-by: Divya Indi <divya.indi@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>
Conflicts:
	net/core/rtnetlink.c
	(Precedes commits that added VF stats, VF trust, vlan info)

Signed-off-by: Brian Maly <brian.maly@oracle.com>