amd74xx: remove /proc/ide/amd74xx

This belongs to user-space (and only if really needed).

   text    data     bss     dec     hex filename
   6723    2000      28    8751    222f drivers/ide/pci/amd74xx.o.before
   3833    2000      16    5849    16d9 drivers/ide/pci/amd74xx.o.after

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>