erofs: add manual PSI accounting for the compressed address space

erofs uses an additional address space for compressed data read from disk
in addition to the one directly associated with the inode.  Reading into
the lower address space is open coded using add_to_page_cache_lru instead
of using the filemap.c helper for page allocation micro-optimizations,
which means it is not covered by the MM PSI annotations for ->read_folio
and ->readahead, so add manual ones instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220915094200.139713-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>