GAS client: Make PMF check on RX more consistent

GAS client: Make PMF check on RX more consistent

Use the SA field instead of BSSID in the received Action frame to
determine whether PMF has been negotiated with the transmitter. While
these fields are supposed to be same for Public Action frames from an
AP, it would be possible that a frame is received with different values.
The following operations in gas_query_rx() use SA, so do the same for
the PMF check.

Signed-off-by: Jouni Malinen <j@w1.fi>