Don't hold the info lock when calling sctp_select_a_tag().
Don't hold the info lock when calling sctp_select_a_tag().

This avoids a double lock bug in the NAT colliding state processing
of SCTP. Thanks to Felix Weinrank for finding and reporting this issue in
https://github.com/sctplab/usrsctp/issues/374
He found this bug using fuzz testing.

CoolmanCZ/usrsctp,sctplab/usrsctp,weinrank/usrsctp,weinrank/usrsctp,CoolmanCZ/usrsctp,sctplab/usrsctp,CoolmanCZ/usrsctp,weinrank/usrsctp,sctplab/usrsctp,CoolmanCZ/usrsctp