ctf: drop CONFIG_DT_DISABLE_CTF, ctf.ko, and all that it implies

ctf: drop CONFIG_DT_DISABLE_CTF, ctf.ko, and all that it implies

Now that CTF is decoupled from the kernel build and built into a
separate archive, there is no longer any need to drag around a
fake ctf.ko module to contain the shared and built-in CTF info.
Drop it, and kernel/ctf/, and the code to autoload it when
dtrace.ko is loaded, and move its Kconfig contents into
lib/Kconfig (which used to include kernel/ctf/Kconfig).

Furthermore, now that CTF is built on demand and not unconditionally
built every time the kernel is, there is no longer any need for
the speedup hack CONFIG_DT_DISABLE_CTF.  Drop it.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Reviewed-by: Tomas Jedlicka <tomas.jedlicka@oracle.com>
Reviewed-by: Victor Erminpour <victor.erminpour@oracle.com>
Orabug: 25815362