iwlwifi: mvm: Increase the max remain on channel time

Increase the maximal remain on channel time as longer remain
on channel requests are handled by the FW using fragmented
time events.

This reduces the number of user/kernel space iterations during
flows such as p2p_listen. In addition it is currently required
for flows which require longer duration such as p2p_sd.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>