Need add cmpxchg64(), or will cause compiling issue.

Just define it as cmpxchg(), since cmpxchg() can support 8 bytes.

The related error (with allmodconfig):

  drivers/block/blockconsole.c: In function ‘bcon_advance_console_bytes’:
  drivers/block/blockconsole.c:164:2: error: implicit declaration of function ‘cmpxchg64’ [-Werror=implicit-function-declaration]

Signed-off-by: Chen Gang <redacted>
---
 arch/tile/include/asm/cmpxchg.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/tile/include/asm/cmpxchg.h b/arch/tile/include/asm/cmpxchg.h
index 276f067..7688c28 100644
--- a/arch/tile/include/asm/cmpxchg.h
+++ b/arch/tile/include/asm/cmpxchg.h

@@ -68,6 +68,8 @@ extern unsigned long __cmpxchg_called_with_bad_pointer(void);
 
 #define tas(ptr) (xchg((ptr), 1))
 
+#define cmpxchg64(ptr, o, n)		cmpxchg((ptr), (o), (n))
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_TILE_CMPXCHG_H */

-- 
1.7.7.6