When calculate memory size of an RTE_FLOW_ITEM_TYPE_RAW 's mask
mask->length is not the real size of binary pattern, it should take
spec->length, or memory size will be over counted (0xffff) and invalid
memory be access during following memcpy.
Fixes: d0ad8648b1c5 ("app/testpmd: fix RSS flow action configuration")
Cc: stable@dpdk.org
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>