perf tools: Make sparc64 arch point to sparc

perf tools: Make sparc64 arch point to sparc

The recent build changes cause perf to not compile for sparc64 since the
arch/sparc64/Build file does not exist:

/home/dahern/kernels/linux.git/tools/build/Makefile.build:40: arch/sparc64/Build: No such file or directory

Fix by converting the sparc64 RAW_ARCH to sparc ARCH -- similar to what
is done for x86_64.

Signed-off-by: David Ahern <david.ahern@oracle.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1424306222-96843-1-git-send-email-david.ahern@oracle.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>