scsicam: Fix use of page cache

Convert scsicam to use a folio instead of a page.  There is no need to
check the error flag here; read_cache_folio() will return -EIO if the
folio cannot be read correctly.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

drivers/scsi/scsicam.c

@@ -34,15 +34,14 @@ unsigned char *scsi_bios_ptable(struct block_device *dev)
 {
 	struct address_space *mapping = bdev_whole(dev)->bd_inode->i_mapping;
 	unsigned char *res = NULL;
-	struct page *page;
+	struct folio *folio;
 
-	page = read_mapping_page(mapping, 0, NULL);
-	if (IS_ERR(page))
+	folio = read_mapping_folio(mapping, 0, NULL);
+	if (IS_ERR(folio))
 		return NULL;
 
-	if (!PageError(page))
-		res = kmemdup(page_address(page) + 0x1be, 66, GFP_KERNEL);
-	put_page(page);
+	res = kmemdup(folio_address(folio) + 0x1be, 66, GFP_KERNEL);
+	folio_put(folio);
 	return res;
 }
 EXPORT_SYMBOL(scsi_bios_ptable);