iwlwifi: fix key removal

When trying to remove a key, we always send key
flags just setting the key type, not including
the multicast flag and the key ID. As a result,
whenever any key was removed, the unicast key 0
would be removed, causing a complete connection
loss after the second rekey (the first doesn't
cause a key removal). Fix the key removal code
to include the key ID and multicast flag, thus
removing the correct key.

Cc: stable@vger.kernel.org
Reported-by: Alexander Schnaidt <alex.schnaidt@googlemail.com>
Tested-by: Alexander Schnaidt <alex.schnaidt@googlemail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>