IWYU: missing include cstring in CableDiscoveryData

CableDiscoveryData uses memcpy, without including the header that declares
it. So include <cstring> is required.

Bug: 819294
Change-Id: I1b8157d2565dc1333be51c6371de1f84374ceb65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2247037
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#779358}

device/fido/cable/cable_discovery_data.cc

@@ -4,6 +4,8 @@
 
 #include "device/fido/cable/cable_discovery_data.h"
 
+#include <cstring>
+
 #include "base/time/time.h"
 #include "crypto/random.h"
 #include "device/fido/fido_parsing_utils.h"