ANDROID: mm: export __pte_offset_map/unuse_swap_pte/read_swap_cache_async

Export __pte_offset_map facilitate retrieving the corresponding PTE using PMD and an address.
Add and export unuse_swap_pte to facilitate releasing the PTE resources corresponding to pages preloaded via swapin.
Export read_swap_cache_async to facilitate asynchronously reading pages from the swap partition using PTE-prefetch scanning.

Bug: 415852480
Bug: 423780868
Bug: 436958726

Change-Id: Ie200656ec97b087936ca98c06b0a370f547d5d0a
Signed-off-by: jianhua hao <haojianhua1@xiaomi.com>
(cherry picked from commit 88cb3505)
(cherry picked from commit c5defcb6)
(cherry picked from commit 7f2f532b)
(cherry picked from commit 8b31b48a)