sparc64: Add sensible read values for /proc/<pid>/sparc_adi

sparc64: Add sensible read values for /proc/<pid>/sparc_adi

This patch makes value read from /proc/<pid>/sparc_adi consistent
across platforms that support ADi and ones that do not. When ADI is
not available for a process either due to process being an anonymous
process on an ADI-capable platform or the process is running on a
non-ADI platform, a read from /proc/<pid>/sparc_adi always reads a
value of -1. This patch updates the documentation file as well with
the values for sparc_adi proc file.

Orabug: 25173120

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>