examples/ipv4_multicast: remove useless mbuf info copy
examples/ipv4_multicast: remove useless mbuf info copy

There is no need for these useless information and
it had better be removed in order to not confuse users.

Signed-off-by: Wei Zhao <55941fd0e75edbdf274af2cfac8f147525678f08@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk