h8300: Fix generic mmu_context build

h8300 missed the generic nommu header conversion.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-mm@kvack.org
Fixes: 94f89922 ("asm-generic: add generic MMU versions of mmu context functions")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>