ipv4: ipmr: fix IP_MROUTE_MULTIPLE_TABLES Kconfig dependencies

IP_MROUTE_MULTIPLE_TABLES should depend on IP_MROUTE.
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/ipv4/Kconfig

@@ -252,7 +252,7 @@ config IP_MROUTE
 
 config IP_MROUTE_MULTIPLE_TABLES
 	bool "IP: multicast policy routing"
-	depends on IP_ADVANCED_ROUTER
+	depends on IP_MROUTE && IP_ADVANCED_ROUTER
 	select FIB_RULES
 	help
 	  Normally, a multicast router runs a userspace daemon and decides