clean up duplicated alloc/free_thread_info

We duplicate alloc/free_thread_info defines on many platforms (the
majority uses __get_free_pages/free_pages).  This patch defines common
defines and removes these duplicated defines.
__HAVE_ARCH_THREAD_INFO_ALLOCATOR is introduced for platforms that do
something different.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-mips/thread_info.h b/include/asm-mips/thread_info.h
index b2772df..bb30606 100644
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -82,6 +82,8 @@
 #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
 #define THREAD_MASK (THREAD_SIZE - 1UL)
 
+#define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
+
 #ifdef CONFIG_DEBUG_STACK_USAGE
 #define alloc_thread_info(tsk)					\
 ({								\