net: common metrics init helper for dst_entry

ipv4 and ipv6 both use refcounted metrics if FIB entries have metrics set.
Move the common initialization code to a helper and use for both protocols.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
3 files changed