ipv6: sr: select DST_CACHE by default

When CONFIG_IPV6_SEG6_LWTUNNEL is selected, automatically select DST_CACHE.
This allows to remove multiple ifdefs.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/Kconfig

@@ -307,6 +307,7 @@ config IPV6_SEG6_LWTUNNEL
 	bool "IPv6: Segment Routing Header encapsulation support"
 	depends on IPV6
 	select LWTUNNEL
+	select DST_CACHE
 	---help---
 	  Support for encapsulation of packets within an outer IPv6
 	  header and a Segment Routing Header using the lightweight