[NET_SCHED]: policer: restore compatibility with old iproute binaries

The tc actions increased the size of struct tc_police, which broke
compatibility with old iproute binaries since both the act_police
and the old NET_CLS_POLICE code check for an exact size match.

Since the new members are not even used, the simple fix is to also
accept the size of the old structure. Dumping is not affected since
old userspace will receive a bigger structure, which is handled fine.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>