waffle: upgrade 1.7.0 -> 1.7.2

Upstream now only generates CMake files on Windows, so remove all
references to CMake.

A zsh completion is now installed, remove this for now as we don't really
use zsh.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>