Add generic mechanism for adding vendor elements into frames

Add generic mechanism for adding vendor elements into frames

This adds following new control interface commands to allow arbitrary
vendor elements to be added into number of frames:

VENDOR_ELEM_ADD <frame id> <hexdump of elem(s)>
VENDOR_ELEM_GET <frame id>
VENDOR_ELEM_REMOVE <frame id> <hexdump of elem(s)>
VENDOR_ELEM_REMOVE <frame id> *

The following frames are supported in this commit (additional frames can
be added in the future):

0 = Probe Request frame in P2P device discovery
1 = Probe Response frame from P2P Device role
2 = Probe Response frame from P2P GO
3 = Beacon frame from P2P GO
4 = PD Req
5 = PD Resp
6 = GO Neg Req
7 = GO Neg Resp
8 = GO Neg Conf
9 = Invitation Request
10 = Invitation Response
11 = P2P Association Request
12 = P2P Association Response

One or more vendor element can be added/removed with the commands. The
hexdump of the element(s) needs to contain the full element (id, len,
payload) and the buffer needs to pass IE parsing requirements to be
accepted.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>