Remove unused config.h defines

These were orphaned in pre-4.6 times, with an argument that an
architecture may appear where these may be necessary.  Since that has
not happened in two years, and the whole group kernels are scheduled for
removal, it is unlikely they ever get used again, either.

Change-Id: Ie8e9c12110a889d9b1ed80125feb1ab7de4483cc