Revert "ping: always initialize ->sin6_scope_id and ->sin6_flowinfo"

This reverts commit e218d7ecc14609a085143e42544b9cf2a64b1e53.
Revert "net: ipv6: Add IPv6 support to the ping socket."

This reverts commit c77dc6e5c09f2f437727f2579f45b19d264c2f6a.
Revert "ipv6: introdcue __ipv6_addr_needs_scope_id and ipv6_iface_scope_id helper functions"

This reverts commit ce3ecedb5bf55d348c9b4e4bb459ba4725afc7df.