staging: olpc_dcon: mark driver as broken

The commit eecb3e4e ("staging: olpc_dcon: add OLPC display controller
(DCON) support") added this driver in 2010, and has been in staging since
then. It was marked as broken at some point because it didn't even build
but that got removed once the build issues were addressed.

But it seems that the work to move this driver out of staging has stalled,
the last non-trivial change to fix one of the items mentioned in its todo
file was commit e40219d5

 ("staging: olpc_dcon: allow simultaneous XO-1
and XO-1.5 support") in 2019.

And even if work to destage the driver is resumed, the fbdev subsystem has
been deprecated for a long time and instead it should be ported to DRM.

Now this driver is preventing to land a kernel wide change, that makes the
num_registered_fb symbol to be private to the fbmem.c file.

So let's just mark the driver as broken. Someone can then work on making
it not depend on the num_registered_fb symbol, allowing to drop the broken
dependency again.

Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20220609223424.907174-1-javierm@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>