testptp: Silence compiler warnings on ppc64

When compiling Documentation/ptp/testptp.c the following compiler
warnings are printed out:

Documentation/ptp/testptp.c: In function ‘main’:
Documentation/ptp/testptp.c:367:11: warning: format ‘%lld’ expects argument
    of type ‘long long int’, but argument 3 has type ‘__s64’ [-Wformat=]
           event.t.sec, event.t.nsec);
           ^
Documentation/ptp/testptp.c:505:5: warning: format ‘%lld’ expects argument
    of type ‘long long int’, but argument 2 has type ‘__s64’ [-Wformat=]
     (pct+2*i)->sec, (pct+2*i)->nsec);
     ^
Documentation/ptp/testptp.c:507:5: warning: format ‘%lld’ expects argument
    of type ‘long long int’, but argument 2 has type ‘__s64’ [-Wformat=]
     (pct+2*i+1)->sec, (pct+2*i+1)->nsec);
     ^
Documentation/ptp/testptp.c:509:5: warning: format ‘%lld’ expects argument
    of type ‘long long int’, but argument 2 has type ‘__s64’ [-Wformat=]
     (pct+2*i+2)->sec, (pct+2*i+2)->nsec);

This happens because __s64 is by default defined as "long" on ppc64,
not as "long long". However, to fix these warnings, it's possible to
define the __SANE_USERSPACE_TYPES__ so that __s64 gets defined to
"long long" on ppc64, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>