FT: Clean up wpa_sm_set_ft_params() by using common parse

FT: Clean up wpa_sm_set_ft_params() by using common parse

Instead of parsing the IEs in the callers, use the already existing
parser in wpa_ft.c to handle MDIE and FTIE from initial MD association
response. In addition, this provides more complete access to association
response IEs to FT code which will be needed to fix FT 4-way handshake
message 2/4.