[LLC]: skb allocation size for responses

Allocate the skb for llc responses with the received packet size by
using the size adjustable llc_frame_alloc.
Don't allocate useless extra payload.
Cleanup magic numbers.

So, this fixes oops.
Reported by Jim Westfall:
kernel: skb_over_panic: text:c0541fc7 len:1000 put:997 head:c166ac00 data:c166ac2f tail:0xc166b017 end:0xc166ac80 dev:eth0
kernel: ------------[ cut here ]------------
kernel: kernel BUG at net/core/skbuff.c:95!

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/llc/llc_pdu.c b/net/llc/llc_pdu.c
index fa83243..2e6cb79 100644
--- a/net/llc/llc_pdu.c
+++ b/net/llc/llc_pdu.c
@@ -241,7 +241,7 @@
 	FRMR_INFO_SET_PDU_INFO_2LONG_IND(frmr_info, vzyxw);
 	FRMR_INFO_SET_PDU_INVALID_Nr_IND(frmr_info, vzyxw);
 	FRMR_INFO_SET_PDU_INVALID_Ns_IND(frmr_info, vzyxw);
-	skb_put(skb, 5);
+	skb_put(skb, sizeof(struct llc_frmr_info));
 }
 
 /**