perf probe: Use %td for pointer arithmetic result

%td is for ptrdiff_t, avoiding this warning on 32-bit:

cc1: warnings being treated as errors
builtin-probe.c: In function ‘opt_set_filter’:
builtin-probe.c:176:4: error: format ‘%ld’ expects type ‘long int’, but
argument 3 has type ‘int’

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>