app/testpmd: remove useless casts on statistics
app/testpmd: remove useless casts on statistics

Caught by code review while investigating the fwd stats display code.

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org

Signed-off-by: David Marchand <f28529695cfa9e3e1eb84e7072aa626af4abb18e@redhat.com>
Reviewed-by: Andrew Rybchenko <ac94ab2a8fe9a9a087f6e24dcbc16626b52c07e8@solarflare.com>
Reviewed-by: Maxime Coquelin <9a2667dee3b90866bbc9c2696cff2b7d5616c95a@redhat.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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