GAS: Shorten the duration of the wait for GAS comeback response

GAS: Shorten the duration of the wait for GAS comeback response

When exchanging GAS frames with the AP, the initial response from the AP
may take a while to come, since the AP may need to fetch the info from a
server. The next fragments/comeback response frames should take much
less time since the AP already has all of the info, so the wait time
for these frames can be reduced.

In addition, some drivers, e.g., mac80211, try to combine ROC based flows,
to improve medium utilization. For example, if the requested ROC fits
entirely in a previous requested ROC they can be combined. Thus, reducing
the wait time for the next frames can improve medium utilization.

Shorten the duration of GAS comeback to improve medium utilization and
overall GAS exchange times.

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