6in4: add missing colon when setting default ca_path

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

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

@@ -84,7 +84,7 @@ proto_6in4_setup() {
 		local http="http"
 		local urlget="uclient-fetch"
 		local urlget_opts="-qO-"
-		local ca_path="${SSL_CERT_DIR-/etc/ssl/certs}"
+		local ca_path="${SSL_CERT_DIR:-/etc/ssl/certs}"
 
 		[ -f /lib/libustream-ssl.so ] && http=https
 		[ "$http" = "https" -a -z "$(find $ca_path -name "*.0" 2>/dev/null)" ] && {