Add the following 39 syscalls for m32r:
  sys_add_key, sys_request_key, sys_keyctl, sys_ioprio_set,
  sys_ioprio_get, sys_inotify_init, sys_inotify_add_watch,
  sys_inotify_rm_watch, sys_migrate_pages, sys_openat,
  sys_mkdirat, sys_mknodat, sys_fchownat, sys_futimesat,
  sys_fstatat64, sys_unlinkat, sys_renameat, sys_linkat,
  sys_symlinkat, sys_readlinkat, sys_fchmodat, sys_faccessat,
  sys_pselect6, sys_ppoll, sys_unshare, sys_set_robust_list,
  sys_get_robust_list, sys_splice, sys_sync_file_range,
  sys_tee, sys_vmsplice, sys_move_pages, sys_getcpu, sys_epoll_pwait,
  sys_utimensat, sys_signalfd, sys_timerfd, sys_eventfd, sys_fallocate
Signed-off-by: NHirokazu Takata <takata@linux-m32r.org>

- Separate sys_call_table from arch/m32r/kernel/entry.S and
  move it to arch/m32r/kernel/system_call.S.
- Change sys_call_table section from .data to .rodata.
Signed-off-by: NHirokazu Takata <takata@linux-m32r.org>