Linux 6.0 compat: Check for migratepage VFS (#17217)

The 6.0 kernel removes the 'migratepage' VFS op. Check for
migratepage.

Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org

module/os/linux/zfs/zpl_file.c

@@ -1058,7 +1058,7 @@ const struct address_space_operations zpl_address_space_operations = {
 #endif
 #ifdef HAVE_VFS_MIGRATE_FOLIO
 	.migrate_folio	= migrate_folio,
-#else
+#elif defined(HAVE_VFS_MIGRATEPAGE)
 	.migratepage	= migrate_page,
 #endif
 };