iwlwifi: disable default wildcard ssid scan

iwl_fill_probe_request has used to add a wildcard ssid IE to
any probe request template, now it's disabled and it will
send wildcard ssid only for full scan. Instead, the highest
priority ssid is set to the template.
Due to adding high priority SSID to the template, it reduce
IE len, but since we had only 260 bytes for IEs before changing
allocation size to be dynamic, now we should have a bit more room
for IEs.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>