cfg80211: Allow cfg80211_connect_result() errors to be distinguished

cfg80211: Allow cfg80211_connect_result() errors to be distinguished

Previously, the status parameter to cfg80211_connect_result() was
documented as using WLAN_STATUS_UNSPECIFIED_FAILURE (1) when the real
status code for the failure is not known. This value can be used by an
AP (and often is) and as such, user space cannot distinguish between
explicitly rejected authentication/association and not being able to
even try to associate or not receiving a response from the AP.

Add a new inline function, cfg80211_connect_timeout(), to be used when
the driver knows that the connection attempt failed due to a reason
where connection could not be attempt or no response was received from
the AP. The internal functions now allow a negative status value (-1) to
be used as an indication of this special case. This results in the
NL80211_ATTR_TIMED_OUT to be added to the NL80211_CMD_CONNECT event to
allow user space to determine this case was hit. For backwards
compatibility, NL80211_STATUS_CODE with the value
WLAN_STATUS_UNSPECIFIED_FAILURE is still indicated in the event in such
a case.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
[johannes: fix cfg80211_connect_bss() prototype to use int for status,
 add cfg80211_connect_timeout() to docbook, fix docbook]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>