LoongArch: Add ARCH_HAS_SET_DIRECT_MAP support

LoongArch: Add ARCH_HAS_SET_DIRECT_MAP support

Add set_direct_map_*() functions for setting the direct map alias for
the page to its default permissions and to an invalid state that cannot
be cached in a TLB. (See d253ca0c3 ("x86/mm/cpa: Add set_direct_map_*()
functions")) Add a similar implementation for LoongArch.

This fixes the KFENCE warnings during hibernation:

 ==================================================================
 BUG: KFENCE: invalid read in swsusp_save+0x368/0x4d8

 Invalid read at 0x00000000f7b89a3c:
  swsusp_save+0x368/0x4d8
  hibernation_snapshot+0x3f0/0x4e0
  hibernate+0x20c/0x440
  state_store+0x128/0x140
  kernfs_fop_write_iter+0x160/0x260
  vfs_write+0x2c0/0x520
  ksys_write+0x74/0x160
  do_syscall+0xb0/0x160

 CPU: 0 UID: 0 PID: 812 Comm: bash Tainted: G    B              6.11.0-rc1+ #1566
 Tainted: [B]=BAD_PAGE
 Hardware name: Loongson-LS3A5000-7A1000-1w-CRB, BIOS vUDK2018-LoongArch-V2.0.0 10/21/2022
 ==================================================================

Note: We can only set permissions for KVRANGE/XKVRANGE kernel addresses.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>