selftests: move ia64 tests from Documentation/ia64

Remove ia64 from Makefile to move the test to selftests.

Update ia64 Makefile to work under selftests. ia64 will not be run as part
of selftests suite and will not be included in install targets. They can be
built separately for now.

The original Makefile built this test on all archirectures and this update
doesn't change that.

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>