ice_flow_valid_attr will return zero on success and a negative value
on error.
Current return value check logic is opposite of the expected behavior.
This patch fixes this issue.
Fixes: d76116a467 ("net/ice: add generic flow API")
Cc: stable@dpdk.org
Signed-off-by: Qiming Yang <qiming.yang@intel.com>
Acked-by: Beilei Xing <beilei.xing@intel.com>