[IPV4]: Add support for fwmark masks in routing rules

Add a FRA_FWMASK attributes for fwmark masks. For compatibility a mask of
0xFFFFFFFF is used when a mark value != 0 is sent without a mask.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/fib_rules.h b/include/linux/fib_rules.h
index 2987549..4418c8d 100644
--- a/include/linux/fib_rules.h
+++ b/include/linux/fib_rules.h
@@ -34,12 +34,13 @@
 	FRA_UNUSED3,
 	FRA_UNUSED4,
 	FRA_UNUSED5,
-	FRA_FWMARK,	/* netfilter mark (IPv4/IPv6) */
+	FRA_FWMARK,	/* netfilter mark */
 	FRA_FLOW,	/* flow/class id */
 	FRA_UNUSED6,
 	FRA_UNUSED7,
 	FRA_UNUSED8,
 	FRA_TABLE,	/* Extended table id */
+	FRA_FWMASK,	/* mask for netfilter mark */
 	__FRA_MAX
 };