udf: Convert udf_adinicb_readpage() to udf_adinicb_read_folio()

Now that all three callers have a folio, convert this function to
take a folio, and use the folio APIs.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240417150416.752929-5-willy@infradead.org>