iwlwifi: dvm: query and report WoWLAN wakeup reason

Implement proper WoWLAN wakeup and query the wakeup
reasons, then report them to userspace.

Note that this is tricky: a firmware bug (that has
been fixed in later versions) means that the status
command response isn't properly closed in hardware
and thus won't arrive at the host. Sending another
command after it closes the status response but the
next command gets stuck, etc. We reset the device
after querying though, so this is not a big issue,
just makes for strange code.

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