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/irq_32.h

@@ -0,0 +1,15 @@
+/* irq.h: IRQ registers on the Sparc.
+ *
+ * Copyright (C) 1995, 2007 David S. Miller (davem@davemloft.net)
+ */
+
+#ifndef _SPARC_IRQ_H
+#define _SPARC_IRQ_H
+
+#include <linux/interrupt.h>
+
+#define NR_IRQS    16
+
+#define irq_canonicalize(irq)	(irq)
+
+#endif