riscv/mm: fix build error while PAGE_TABLE_CHECK enabled without MMU

riscv/mm: fix build error while PAGE_TABLE_CHECK enabled without MMU

mm/page_table_check.c: In function `__page_table_check_pte_clear':
mm/page_table_check.c:148:6: error: implicit declaration of function `pte_user_accessible_page'; did you mean `user_access_save'? [-Werror=implicit-function-declaration]
  if (pte_user_accessible_page(pte)) {
      ^~~~~~~~~~~~~~~~~~~~~~~~
      user_access_save

ARCH_SUPPORTS_PAGE_TABLE_CHECK should only enabled with MMU.

Link: https://lkml.kernel.org/r/20220624085236.18544-1-yuehaibing@huawei.com
Fixes: 3fee229a8eb9 ("riscv/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>