net: af_packet: fix procfs header for 64-bit pointers

On 64-bit systems the packet procfs header field names following 'sk'
are not aligned correctly:

sk       RefCnt Type Proto  Iface R Rmem   User   Inode
00000000605d2c64 3      3    0003   7     1 450880 0      16643
00000000080e9b80 2      2    0000   0     0 0      0      17404
00000000b23b8a00 2      2    0000   0     0 0      0      17421
...

With this change field names are correctly aligned:

sk               RefCnt Type Proto  Iface R Rmem   User   Inode
000000005c3b1d97 3      3    0003   7     1 21568  0      16178
000000007be55bb7 3      3    fbce   8     1 0      0      16250
00000000be62127d 3      3    fbcd   8     1 0      0      16254
...
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Link: https://lore.kernel.org/r/54917251d8433735d9a24e935a6cb8eb88b4058a.1608103684.git.baruch@tkos.co.ilSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/packet/af_packet.c

@@ -4595,7 +4595,9 @@ static void packet_seq_stop(struct seq_file *seq, void *v)
 static int packet_seq_show(struct seq_file *seq, void *v)
 {
 	if (v == SEQ_START_TOKEN)
-		seq_puts(seq, "sk       RefCnt Type Proto  Iface R Rmem   User   Inode\n");
+		seq_printf(seq,
+			   "%*sRefCnt Type Proto  Iface R Rmem   User   Inode\n",
+			   IS_ENABLED(CONFIG_64BIT) ? -17 : -9, "sk");
 	else {
 		struct sock *s = sk_entry(v);
 		const struct packet_sock *po = pkt_sk(s);