arch/tile: prefer "tilepro" as the name of the 32-bit architecture

With this change, you can (and should) build with ARCH=tilepro for the
current 32-bit chips.  Building with ARCH=tile continues to work, but
we've renamed the defconfig file to tilepro_defconfig for consistency.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

Makefile

@@ -221,6 +221,9 @@ ifeq ($(ARCH),sh64)
 endif
 
 # Additional ARCH settings for tile
+ifeq ($(ARCH),tilepro)
+       SRCARCH := tile
+endif
 ifeq ($(ARCH),tilegx)
        SRCARCH := tile
 endif