jfs: jump to error_out when filemap_{fdatawait, write_and_wait} fails

filemap_fdatawait/filemap_write_and_wait may fail, so check the return
value and jump to error_out in the case of error.

Signed-off-by: Quorum Laval <quorum.laval@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>