If error occurs, leave lookup parameter untouched.

There is no functional change, since all current callers just bail out
in case of error without using the assigned pieces.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>