[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/meth.c b/drivers/net/meth.c
index fafe678..0343ea1 100644
--- a/drivers/net/meth.c
+++ b/drivers/net/meth.c
@@ -608,7 +608,7 @@
 
 	desc->header.raw = METH_TX_CMD_INT_EN | (len-1) | ((128-len) << 16);
 	/* maybe I should set whole thing to 0 first... */
-	memcpy(desc->data.dt + (120 - len), skb->data, skb->len);
+	skb_copy_from_linear_data(skb, desc->data.dt + (120 - len), skb->len);
 	if (skb->len < len)
 		memset(desc->data.dt + 120 - len + skb->len, 0, len-skb->len);
 }
@@ -626,8 +626,8 @@
 
 	/* unaligned part */
 	if (unaligned_len) {
-		memcpy(desc->data.dt + (120 - unaligned_len),
-		       skb->data, unaligned_len);
+		skb_copy_from_linear_data(skb, desc->data.dt + (120 - unaligned_len),
+			      unaligned_len);
 		desc->header.raw |= (128 - unaligned_len) << 16;
 	}
 
@@ -652,8 +652,8 @@
 	desc->header.raw = METH_TX_CMD_INT_EN | TX_CATBUF1 | TX_CATBUF2| (skb->len - 1);
 	/* unaligned part */
 	if (unaligned_len){
-		memcpy(desc->data.dt + (120 - unaligned_len),
-		       skb->data, unaligned_len);
+		skb_copy_from_linear_data(skb, desc->data.dt + (120 - unaligned_len),
+			      unaligned_len);
 		desc->header.raw |= (128 - unaligned_len) << 16;
 	}