ip_frag: revert fix fragmenting IPv4 fragment

The patch ("ip_frag: fix fragmenting IPv4 fragment") introduces
a bug and needs to be rolled back. This is because the patch
and variables "flag_offset" conflict with each other.

Bugzilla ID: 835
Fixes: 5674734 ("ip_frag: fix fragmenting IPv4 fragment")
Cc: stable@dpdk.org

Signed-off-by: Huichao Cai <chcchc88@163.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

Author: chcchc88

lib/ip_frag/rte_ipv4_fragmentation.c

@@ -75,7 +75,7 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
 	uint32_t out_pkt_pos, in_seg_data_pos;
 	uint32_t more_in_segs;
 	uint16_t fragment_offset, flag_offset, frag_size, header_len;
-	uint16_t frag_bytes_remaining, not_last_frag;
+	uint16_t frag_bytes_remaining;
 
 	/*
 	 * Formal parameter checking.
@@ -116,9 +116,7 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
 	in_seg = pkt_in;
 	in_seg_data_pos = header_len;
 	out_pkt_pos = 0;
-	fragment_offset = (uint16_t)((flag_offset &
-	    RTE_IPV4_HDR_OFFSET_MASK) << RTE_IPV4_HDR_FO_SHIFT);
-	not_last_frag = (uint16_t)(flag_offset & IPV4_HDR_MF_MASK);
+	fragment_offset = 0;
 
 	more_in_segs = 1;
 	while (likely(more_in_segs)) {
@@ -188,8 +186,7 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
 
 		__fill_ipv4hdr_frag(out_hdr, in_hdr, header_len,
 		    (uint16_t)out_pkt->pkt_len,
-		    flag_offset, fragment_offset,
-		    not_last_frag || more_in_segs);
+		    flag_offset, fragment_offset, more_in_segs);
 
 		fragment_offset = (uint16_t)(fragment_offset +
 		    out_pkt->pkt_len - header_len);