[SK_BUFF]: Introduce skb_copy_from_linear_data{_offset}

To clearly state the intent of copying from linear sk_buffs, _offset being a
overly long variant but interesting for the sake of saving some bytes.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/drivers/net/sgiseeq.c b/drivers/net/sgiseeq.c
index 5a89191..d8c9c5d 100644
--- a/drivers/net/sgiseeq.c
+++ b/drivers/net/sgiseeq.c
@@ -534,7 +534,7 @@
 	 *    entry and the HPC got to the end of the chain before we
 	 *    added this new entry and restarted it.
 	 */
-	memcpy((char *)(long)td->buf_vaddr, skb->data, skblen);
+	skb_copy_from_linear_data(skb, (char *)(long)td->buf_vaddr, skblen);
 	if (len != skblen)
 		memset((char *)(long)td->buf_vaddr + skb->len, 0, len-skblen);
 	td->tdma.cntinfo = (len & HPCDMA_BCNT) |