ofp-actions: Make encap action really require OF1.3+.

ofp-actions: Make encap action really require OF1.3+.

This action is only supported in OpenFlow 1.3 and later, but the parser
from text allowed it in earlier versions, which could cause confusion,
e.g.:

$ ovs-ofctl parse-flow 'actions=encap(ethernet())'
usable protocols: any
chosen protocol: OpenFlow10-table_id
2019-04-30T20:19:59Z|00001|ofp_actions|WARN|unknown OpenFlow10 action for vendor 0x2320 and type 46
2019-04-30T20:19:59Z|00002|ofp_actions|WARN|bad action at offset 0 (OFPBAC_BAD_VENDOR_TYPE):
00000000  ff ff 00 10 00 00 23 20-00 2e 00 00 00 00 00 00
OFPT_FLOW_MOD (xid=0x1): ***decode error: OFPBAC_BAD_VENDOR_TYPE***
00000000  01 0e 00 58 00 00 00 01-00 38 20 ff 00 00 00 00 |...X.....8 .....|
00000010  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 |................|
00000020  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 |................|
00000030  00 00 00 00 00 00 00 00-00 00 00 00 00 00 80 00 |................|
00000040  ff ff ff ff ff ff 00 00-ff ff 00 10 00 00 23 20 |..............# |
00000050  00 2e 00 00 00 00 00 00-                        |........        |

Acked-by: Numan Siddique <nusiddiq@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>