can: proc: fix rcvlist_* header alignment on 64-bit system

Before this fix, the function and userdata columns weren't aligned:
  device   can_id   can_mask  function  userdata   matches  ident
   vcan0  92345678  9fffffff  0000000000000000  0000000000000000         0  raw
   vcan0     123    00000123  0000000000000000  0000000000000000         0  raw

After the fix they are:
  device   can_id   can_mask      function          userdata       matches  ident
   vcan0  92345678  9fffffff  0000000000000000  0000000000000000         0  raw
   vcan0     123    00000123  0000000000000000  0000000000000000         0  raw

Link: Link: https://lore.kernel.org/r/20210425141440.229653-1-erik@flodin.me
Signed-off-by: Erik Flodin <erik@flodin.me>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>