[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/include/linux/skbuff.h b/include/linux/skbuff.h
index 1c19b2d..08c96bc 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1507,6 +1507,20 @@
 	return buffer;
 }
 
+static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
+					     void *to,
+					     const unsigned int len)
+{
+	memcpy(to, skb->data, len);
+}
+
+static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
+						    const int offset, void *to,
+						    const unsigned int len)
+{
+	memcpy(to, skb->data + offset, len);
+}
+
 extern void skb_init(void);
 
 /**