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

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.il
Signed-off-by: Jakub Kicinski <kuba@kernel.org>