sparc64: Fix rwsem constant bug leading to hangs.

[ Upstream commit ef201beb ]

As noticed by Linus, it is critical that some of the
rwsem constants be signed.  Yet, hex constants are
unsigned unless explicitly casted or negated.

The most critical one is RWSEM_WAITING_BIAS.

This bug was exacerbated by commit
424acaae ("rwsem: wake queued readers
when writer blocks on active read lock")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/sparc/include/asm/rwsem-const.h

@@ -5,7 +5,7 @@
 #define RWSEM_UNLOCKED_VALUE		0x00000000
 #define RWSEM_ACTIVE_BIAS		0x00000001
 #define RWSEM_ACTIVE_MASK		0x0000ffff
-#define RWSEM_WAITING_BIAS		0xffff0000
+#define RWSEM_WAITING_BIAS		(-0x00010000)
 #define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
 #define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)