6in4: remove 6in4 tunnel delete workaround (FS#3690)

Remove 6in4 tunnel delete workaround as the real issue is
now solved in netifd
(https://git.openwrt.org/?p=project/netifd.git;a=commit;h=8f82742ca4f47f459284f3a07323d04da72ea5f6

)

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

package/network/ipv6/6in4/Makefile

@@ -8,7 +8,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=6in4
-PKG_RELEASE:=27
+PKG_RELEASE:=28
 PKG_LICENSE:=GPL-2.0
 
 include $(INCLUDE_DIR)/package.mk

package/network/ipv6/6in4/files/6in4.sh

@@ -138,8 +138,6 @@ proto_6in4_setup() {
 
 proto_6in4_teardown() {
 	local cfg="$1"
-	local link="6in4-$cfg"
-	ip link del $link
 }
 
 proto_6in4_init_config() {