app/testpmd: fix crash when mempool allocation fails
app/testpmd: fix crash when mempool allocation fails

Avoid access to mempool pointer if it is NULL.

Coverity issue: 127553
Fixes: b19a0c75a0d4 ("app/testpmd: remove anonymous mempool code")

Signed-off-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>
Acked-by: Pablo de Lara <28355d9cfe41bb8148aea0fb24f47aae8f4217a1@intel.com>

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