net/eth: Better describe _eth_get_rss_ex_dst_addr's offset argument

The 'offset' argument represents the offset to the ip6_ext_hdr
header, rename it as 'ext_hdr_offset'.

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Miroslav Rezanina <mrezanin@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/eth.c

@@ -401,7 +401,7 @@ eth_is_ip6_extension_header_type(uint8_t hdr_type)
 
 static bool
 _eth_get_rss_ex_dst_addr(const struct iovec *pkt, int pkt_frags,
-                        size_t rthdr_offset,
+                        size_t ext_hdr_offset,
                         struct ip6_ext_hdr *ext_hdr,
                         struct in6_address *dst_addr)
 {
@@ -412,12 +412,12 @@ _eth_get_rss_ex_dst_addr(const struct iovec *pkt, int pkt_frags,
         size_t input_size = iov_size(pkt, pkt_frags);
         size_t bytes_read;
 
-        if (input_size < rthdr_offset + sizeof(*ext_hdr)) {
+        if (input_size < ext_hdr_offset + sizeof(*ext_hdr)) {
             return false;
         }
 
         bytes_read = iov_to_buf(pkt, pkt_frags,
-                                rthdr_offset + sizeof(*rthdr),
+                                ext_hdr_offset + sizeof(*rthdr),
                                 dst_addr, sizeof(*dst_addr));
 
         return bytes_read == sizeof(*dst_addr);