Generic semaphore implementation

Semaphores are no longer performance-critical, so a generic C
implementation is better for maintainability, debuggability and
extensibility.  Thanks to Peter Zijlstra for fixing the lockdep
warning.  Thanks to Harvey Harrison for pointing out that the
unlikely() was unnecessary.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-um/semaphore.h b/include/asm-um/semaphore.h
index ff13c34..d9b2034 100644
--- a/include/asm-um/semaphore.h
+++ b/include/asm-um/semaphore.h
@@ -1,6 +1 @@
-#ifndef __UM_SEMAPHORE_H
-#define __UM_SEMAPHORE_H
-
-#include "asm/arch/semaphore.h"
-
-#endif
+#include <linux/semaphore.h>