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>
diff --git a/Makefile b/Makefile
index 40f2481..baee3d4 100644
--- a/Makefile
+++ b/Makefile
@@ -206,7 +206,11 @@
 endif
 
 # Where to locate arch specific headers
-hdr-arch       := $(SRCARCH)
+ifeq ($(ARCH),sparc64)
+       hdr-arch  := sparc
+else
+       hdr-arch  := $(SRCARCH)
+endif
 
 KCONFIG_CONFIG	?= .config