m68k: /proc/hardware should depend on PROC_FS

When CONFIG_PROC_FS is not set, there is a build error for an unused
function. Make PROC_HARDWARE depend on PROC_FS to prevent this error.

In file included from ../arch/m68k/kernel/setup.c:3:
../arch/m68k/kernel/setup_mm.c:477:12: error: 'hardware_proc_show' defined but not used [-Werror=unused-function]
  477 | static int hardware_proc_show(struct seq_file *m, void *v)
      |            ^~~~~~~~~~~~~~~~~~

Fixes: 66d857b0

 ("m68k: merge m68k and m68knommu arch directories") # v3.0
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230209010825.24136-1-rdunlap@infradead.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>