Add missing return after setting the error status in case of
invalid flush_flag in the operation.
The issue was found by the coverity scan as the fin_flush variable,
not initialized in such case, was used later in the flow.
Coverity issue: 340859
Fixes: c7b436ec95fd ("compress/zlib: support burst enqueue/dequeue")
Cc: stable@dpdk.org
Signed-off-by: Adam Dybkowski <adamx.dybkowski@intel.com>
ff53baa9cc