bcmring: drop commented out line in Kconfig

There's no file named "drivers/char/bcmring/Kconfig". It seems it has
never been part of the mainline kernel tree. So there's nothing to be
sourced here.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>