Input: hilkbd - Add casts to HP9000/300 I/O accessors

Internally, hilkbd uses "unsigned long" I/O addresses everywhere.
This works fine as:
  - On PA-RISC, hilkbd uses the gsc_{read,write}b() I/O accessors, which
    take "unsigned long" addresses,
  - On m68k, hilkbd uses {read,write}b(), which are currently mapped to
    {in,out}_8(), and convert the passed addresses to pointers
    internally.

However, the asm-generic version of {read,write}b() does not perform
such conversions, and requires passing pointers instead.  Hence add
casts to prepare for switching m68k to the asm-generic version.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Greg Ungerer <gerg@linux-m68k.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>