net: em_canid: Ematch rule to match CAN frames according to their identifiers

This ematch makes it possible to classify CAN frames (AF_CAN) according
to their identifiers. This functionality can not be easily achieved with
existing classifiers, such as u32, because CAN identifier is always stored
in native endianness, whereas u32 expects Network byte order.

Signed-off-by: Rostislav Lisovy <lisovy@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/include/linux/pkt_cls.h b/include/linux/pkt_cls.h
index defbde2..38fbd4b 100644
--- a/include/linux/pkt_cls.h
+++ b/include/linux/pkt_cls.h
@@ -451,8 +451,9 @@
 #define	TCF_EM_U32		3
 #define	TCF_EM_META		4
 #define	TCF_EM_TEXT		5
-#define        TCF_EM_VLAN		6
-#define	TCF_EM_MAX		6
+#define	TCF_EM_VLAN		6
+#define	TCF_EM_CANID		7
+#define	TCF_EM_MAX		7
 
 enum {
 	TCF_EM_PROG_TC