[coreboot] the eternal pre-post car debate in v3

[ron minnich]

W.r.t. Kevin's question: if we wrote stage1 as follows:

stage1(){
.
.
.
  disable_car();
  stage1_after_car();
}

How would people feel about that?

There are still real concerns in my mind about lingering addresses in
registers that gcc might leave hanging around. The call nicely removes
the worries.

ron