sched: remove useless malloc in PIE data init

sched: remove useless malloc in PIE data init

'rte_pie_rt_data_init(NULL)' is not expected, and it's ought to
fail when this happen. The malloc inside the function didn't work.
So remove the malloc otherwise will lead to a memory leak.

Fixes: 44c730b0e37971 ("sched: add PIE based congestion management")
Cc: stable@dpdk.org
Signed-off-by: Weiguo Li <liwg06@foxmail.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>