misc changes including WSC M1 and M2 verification

is_cmdu_type_response() returns true only for response to unicast type.
cmdu_alloc_simple() returns assigned 'mid' when passed as 0.
record receiving interface name in 'dev_ifname' of struct cmdu_buff.
Extend 'cmdu_ackq' to allow passing of user cookie so that it can be checked
in the response path, if needed.
Fix ap autoconfig search and response handling.
Fix WSC M2 message construction and processing.