perf trace: Fix ioctl 'request' beautifier build problems on !(i386 || x86_64) arches

Supporting decoding the ioctl 'request' parameter needs more work to
properly support more architectures, the current approach doesn't work
on at least powerpc and sparc, as reported by Ben Hutchings in
http://lkml.kernel.org/r/1391593985.3003.48.camel@deadeye.wl.decadent.org.uk .

Work around that by making it to be ifdefed for the architectures known
to work with the current, limited approach, i386 and x86_64 till better
code is written.

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: <stable@vger.kernel.org> # 3.13 Fixes: 78645cf3

 ("perf trace: Initial beautifier for ioctl's 'cmd' arg")
Link: http://lkml.kernel.org/n/tip-ss04k11insqlu329xh5g02q0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>