Documentation: remove depends on CONFIG_EXPERIMENTAL

The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.

CC: Rob Landley <rob@landley.net>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Masanari Iida <standby24x7@gmail.com>
CC: Jason Wessel <jason.wessel@windriver.com>
CC: Richard L Maliszewski <richard.l.maliszewski@intel.com>
CC: Gang Wei <gang.wei@intel.com>
CC: Shane Wang <shane.wang@intel.com>
CC: Harry Wei <harryxiyou@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Jason Wessel <jason.wessel@windriver.com>