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/scatterlist_64.h

@@ -0,0 +1,27 @@
+#ifndef _SPARC64_SCATTERLIST_H
+#define _SPARC64_SCATTERLIST_H
+
+#include <asm/page.h>
+#include <asm/types.h>
+
+struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
+	unsigned long	page_link;
+	unsigned int	offset;
+
+	unsigned int	length;
+
+	dma_addr_t	dma_address;
+	__u32		dma_length;
+};
+
+#define sg_dma_address(sg)	((sg)->dma_address)
+#define sg_dma_len(sg)     	((sg)->dma_length)
+
+#define ISA_DMA_THRESHOLD	(~0UL)
+
+#define ARCH_HAS_SG_CHAIN
+
+#endif /* !(_SPARC64_SCATTERLIST_H) */