iwmc3200wifi: handling wifi_if_ntfy responses

When we're calling iwm_send_wifi_if_cmd() with the resp flag set, we're
currently waiting on the mlme queue, waiting for some flags here and there to
show up.
This patch adds a wifi_ntfy bitmap, and when we're sending a wifi_if command
expecting an answers, we wait synchronously for it to show up, on a dedicated
queue. The wifi_ntfy bit is set when we receive the corresponding answer.

Signed-off-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>