GAS: End remain-on-channel due to delayed GAS comeback request

GAS: End remain-on-channel due to delayed GAS comeback request

During the sequence of exchanging GAS frames with the AP, the AP can
request to come back in X amount of time and resend the GAS request.

Previously, wpa_supplicant did not terminate the remain-on-channel
session, but rather waited until the requested comeback delay had
expired, and then tried to send the GAS frame (potentially to save the
time that is required to schedule a new remain on channel flow).

This might cause unnecessary idle time (can be close to 1000 ms) in
which the device might be off-channel. Ending the current
remain-on-channel session and then rescheduling makes better usage of
the time in this case.

End remain-on-channel session due to receiving a delayed GAS comeback
request from the AP.

Signed-off-by: Matti Gottlieb <matti.gottlieb@intel.com>