skbuff: size of hole is wrong in a comment

Since commit c93bdd0e ("netvm: allow skb allocation to use PFMEMALLOC
reserves"), hole size is one bit less than what is written in the comment.
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -498,7 +498,7 @@ struct sk_buff {
 	 * headers if needed
 	 */
 	__u8			encapsulation:1;
-	/* 7/9 bit hole (depending on ndisc_nodetype presence) */
+	/* 6/8 bit hole (depending on ndisc_nodetype presence) */
 	kmemcheck_bitfield_end(flags2);
 
 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL