ocfs2: convert ocfs2_map_page_blocks to use a folio

ocfs2: convert ocfs2_map_page_blocks to use a folio

Convert the page argument to a folio and then use the folio APIs
throughout.  Replaces three hidden calls to compound_head() with one
explicit one.

Link: https://lkml.kernel.org/r/20231016201114.1928083-22-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>