UPSTREAM: f2fs: convert __f2fs_write_meta_page() to use folio

Convert to use folio, so that we can get rid of 'page->index' to
prepare for removal of 'index' field in structure page [1].

[1] https://lore.kernel.org/all/Zp8fgUSIBGQ1TN0D@casper.infradead.org/



Cc: Matthew Wilcox <willy@infradead.org>
Change-Id: I31b96e2082e4a192595a434a2156225f35c7db85
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 138a762e)