tile: expose number of page table levels

We would want to use number of page table level to define mm_struct.
Let's expose it as CONFIG_PGTABLE_LEVELS.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Chris Metcalf <cmetcalf@ezchip.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/tile/Kconfig

@@ -147,6 +147,11 @@ config ARCH_DEFCONFIG
 	default "arch/tile/configs/tilepro_defconfig" if !TILEGX
 	default "arch/tile/configs/tilegx_defconfig" if TILEGX
 
+config PGTABLE_LEVELS
+	int
+	default 3 if 64BIT
+	default 2
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"