Documentation/kernel-parameters: remove autotest and mcatest

It has no more users, the last one is gone in "[PATCH] ia64: Kconfig
cleanup" aka ("6fd79ab50b").
mcatest is gone in commit "[PATCH] ia64: SGI SN update"
("c6bacd5010ec").

Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>