Fragmentation is not used with multicast frames. Discard unexpected
fragments with multicast DA. This fixes CVE-2020-26145.

Tested-on: QCA6174 hw3.2 SDIO WLAN.RMH.4.4.1-00049

Cc: stable@vger.kernel.org
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Link: https://lore.kernel.org/r/20210511200110.9ca6ca7945a9.I1e18b514590af17c155bda86699bc3a971a8dcf4@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>