arch/tile: mark as orphaned

The chip family of TILEPro and TILE-Gx was developed by Tilera, which
was eventually acquired by Mellanox.  The tile architecture was added to
the kernel in 2010 and first appeared in 2.6.36.

Now at Mellanox we are developing new chips based on the ARM64
architecture; our last TILE-Gx chip (the Gx72) was released in 2013, and
our customers using tile architecture products are not, as far as we
know, looking to upgrade to newer kernel releases.  In the absence of
someone in the community stepping up to take over maintainership, this
commit marks the architecture as orphaned.

Cc: Chris Metcalf <metcalf@alum.mit.edu>
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>