Blackfin: convert to asm-generic/mutex-dec.h for all systems

The Blackfin mutex.h is merely a copy of an older asm-generic/mutex-dec.h,
so punt it and just use the common one directly.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/mutex.h

-/*
- * Pull in the generic implementation for the mutex fastpath.
- *
- * TODO: implement optimized primitives instead, or leave the generic
- * implementation in place, or pick the atomic_xchg() based generic
- * implementation. (see asm-generic/mutex-xchg.h for details)
- *
- * Copyright 2006-2009 Analog Devices Inc.
- *
- * Licensed under the GPL-2 or later.
- */
-
-#ifndef _ASM_MUTEX_H
-#define _ASM_MUTEX_H
-
-#ifndef CONFIG_SMP
-#include <asm-generic/mutex.h>
-#else
-
-static inline void
-__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
-{
-	if (unlikely(atomic_dec_return(count) < 0))
-		fail_fn(count);
-	else
-		smp_mb();
-}
-
-static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
-{
-	if (unlikely(atomic_dec_return(count) < 0))
-		return fail_fn(count);
-	else {
-		smp_mb();
-		return 0;
-	}
-}
-
-static inline void
-__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
-{
-	smp_mb();
-	if (unlikely(atomic_inc_return(count) <= 0))
-		fail_fn(count);
-}
-
-#define __mutex_slowpath_needs_to_unlock()		1
-
-static inline int
-__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
-{
-	/*
-	 * We have two variants here. The cmpxchg based one is the best one
-	 * because it never induce a false contention state.  It is included
-	 * here because architectures using the inc/dec algorithms over the
-	 * xchg ones are much more likely to support cmpxchg natively.
-	 *
-	 * If not we fall back to the spinlock based variant - that is
-	 * just as efficient (and simpler) as a 'destructive' probing of
-	 * the mutex state would be.
-	 */
-#ifdef __HAVE_ARCH_CMPXCHG
-	if (likely(atomic_cmpxchg(count, 1, 0) == 1)) {
-		smp_mb();
-		return 1;
-	}
-	return 0;
-#else
-	return fail_fn(count);
-#endif
-}
-
-#endif
-
-#endif
+#include <asm-generic/mutex-dec.h>