selftests/vm: add a test for virtual address range mapping

selftests/vm: add a test for virtual address range mapping

This verifies virtual address mapping below and above the 128TB range
and makes sure that address returned are within the expected range
depending upon the hint passed from the user space.

Link: http://lkml.kernel.org/r/20170418095252.20533-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Michal Suchanek <msuchanek@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>