The only think I have seen as far as hardware recommendations for Photoshop was posted for CS6. Laptops these days are quite powerful you should be able to find one with specs that will fit your bill. If you will only be using it occasionally you need not go all out. Top of the chain Laptops always have a high premium added to their price.
http://blogs.adobe.com/jnack/files/2012/07/CS6_hardware_recommendations.pdf