parisc: PDT: Fix missing prototype warning

parisc: PDT: Fix missing prototype warning

As reported by the kernel test robot, the following error occurs:

arch/parisc/kernel/pdt.c:65:6: warning: no previous prototype for 'arch_report_meminfo' [-Wmissing-prototypes]
      65 | void arch_report_meminfo(struct seq_file *m)
         |      ^~~~~~~~~~~~~~~~~~~

arch_report_meminfo() is declared in include/linux/proc_fs.h and only
defined when CONFIG_PROC_FS is enabled. Wrap its definition in #ifdef
CONFIG_PROC_FS to fix the -Wmissing-prototypes warning.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202502082315.IPaHaTyM-lkp@intel.com/
Signed-off-by: Yu-Chun Lin <eleanor15x@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>