MIPS: barrier: Remove fast_mb() Octeon #ifdef'ery

The definition of fast_mb() is the same in both the Octeon & non-Octeon
cases, so remove the duplication & define it only once.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

arch/mips/include/asm/barrier.h

@@ -38,6 +38,8 @@ static inline void wmb(void)
 }
 #define wmb wmb
 
+#define fast_mb()	__sync()
+
 #define __fast_iob()				\
 	__asm__ __volatile__(			\
 		".set	push\n\t"		\
@@ -49,10 +51,8 @@ static inline void wmb(void)
 		: "m" (*(int *)CKSEG1)		\
 		: "memory")
 #ifdef CONFIG_CPU_CAVIUM_OCTEON
-# define fast_mb()	__sync()
 # define fast_iob()	do { } while (0)
 #else /* ! CONFIG_CPU_CAVIUM_OCTEON */
-# define fast_mb()	__sync()
 # ifdef CONFIG_SGI_IP28
 #  define fast_iob()				\
 	__asm__ __volatile__(			\