iwlwifi: remove implicit direct scan

When an undirected scan is requested and iwlwifi is not associated but
the user has set an SSID (and maybe was associated with that network at
some point) then iwlwifi will assume the user wanted to scan for this
SSID which seems wrong. Remove this code.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>