char/misc: remove CONFIG_EXPERIMENTAL dependencies

As discussed at the kernel summit this year, CONFIG_EXPERIMENTAL means
nothing, so let's get rid of it.

Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>