bridge: implement rtnl_link_ops->get_size and rtnl_link_ops->fill_info

Allow rtnetlink users to get bridge master info in IFLA_INFO_DATA attr
This initial part implements forward_delay, hello_time, max_age options.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_link.h

@@ -215,6 +215,18 @@ enum in6_addr_gen_mode {
 	IN6_ADDR_GEN_MODE_NONE,
 };
 
+/* Bridge section */
+
+enum {
+	IFLA_BR_UNSPEC,
+	IFLA_BR_FORWARD_DELAY,
+	IFLA_BR_HELLO_TIME,
+	IFLA_BR_MAX_AGE,
+	__IFLA_BR_MAX,
+};
+
+#define IFLA_BR_MAX	(__IFLA_BR_MAX - 1)
+
 enum {
 	BRIDGE_MODE_UNSPEC,
 	BRIDGE_MODE_HAIRPIN,