coccinelle: adjust NULL check before free()

The free() function checks if its argument is NULL. We should avoid
checking for NULL before calling free like in

    if (result->tds)
        free(result->tds);

The list of relevant functions differs between Linux and U-Boot, e.g. we
use free().

Adjust the list of relevant functions.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>