sparc, sparc64: use arch/sparc/include

The majority of this patch was created by the following script:

***
ASM=arch/sparc/include/asm
mkdir -p $ASM
git mv include/asm-sparc64/ftrace.h $ASM
git rm include/asm-sparc64/*
git mv include/asm-sparc/* $ASM
sed -ie 's/asm-sparc64/asm/g' $ASM/*
sed -ie 's/asm-sparc/asm/g' $ASM/*
***

The rest was an update of the top-level Makefile to use sparc
for header files when sparc64 is being build.
And a small fixlet to pick up the correct unistd.h from
sparc64 code.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

arch/sparc/include/asm/hardirq_64.h

@@ -0,0 +1,19 @@
+/* hardirq.h: 64-bit Sparc hard IRQ support.
+ *
+ * Copyright (C) 1997, 1998, 2005 David S. Miller (davem@davemloft.net)
+ */
+
+#ifndef __SPARC64_HARDIRQ_H
+#define __SPARC64_HARDIRQ_H
+
+#include <asm/cpudata.h>
+
+#define __ARCH_IRQ_STAT
+#define local_softirq_pending() \
+	(local_cpu_data().__softirq_pending)
+
+void ack_bad_irq(unsigned int irq);
+
+#define HARDIRQ_BITS	8
+
+#endif /* !(__SPARC64_HARDIRQ_H) */