app/test: fix mempool freeing
app/test: fix mempool freeing

test_mempool func not using pointer variable 'mp_ext' and incorrectly
freed. So removing ptr var. Now freeing mp_stack var.

Fixes: ea151eb48a04 ("app/test: migrate custom mempool handler to stack handler")

Signed-off-by: Santosh Shukla <23b682afe3504ae4f88c66c3cabfb34f87e9916e@caviumnetworks.com>
Acked-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>

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