cmake: Always put cmake package files in -dev packages

cmake: Always put cmake package files in -dev packages

Various recipes that inherit cmake contain FILES_${PN}-dev magic to add the
generated package files to their -dev packages. Since this is a standard
feature of cmake, we might as well teach cmake.bbclass to do this itself so
those recipes can be simpler.

Signed-off-by: Mike Crowe <mac@mcrowe.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>