tile: Use common threadinfo allocator

Use the core allocator and deal with the extra cleanup in
arch_release_thread_info().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Link: http://lkml.kernel.org/r/20120505150142.311126440@linutronix.de