macros and dtc

[Kumar Gala]

After spending some time this weekend cleaning up dts files I figured  
it would be nice if we can some to consensus on how we are going to  
do macro support.  There is clearly a lot of duplication between  
dts's and it only gets worse when you add in slight variations for  
revs of boards.

I wasn't sure if we are thinking of using some style of preprocessor  
(cpp, m4, etc..) or trying to add something into dtc itself.

However, I think it would be good for us to get some traction towards  
a solution for in kernel dts files.

- k