radeon: Drop the non-kernel-memory-manager support, and thus DRI1.

radeon: Drop the non-kernel-memory-manager support, and thus DRI1.

It's past time, and it was going to get in the way of the renderbuffer
mapping refactor.  We dropped all the other DRI1 drivers for this
release, and I can't imagine anybody supporting DRI1 radeon classic in
a new release of Mesa.

Diff produced by treating kernel_mm as true, deleting the DRI1 paths
that produce kernel_mm false, and deleting code.