tools lib traceevent: Fix conversion of pointer to integer of different size

gcc complaint on 32-bit system:

/home/acme/git/linux/tools/lib/traceevent/event-parse.c: In function ‘eval_num_arg’:
/home/acme/git/linux/tools/lib/traceevent/event-parse.c:3468:9: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]

This is because the eval_num_arg returns everything as an 'unsigned long long',
so it converts a void pointer to a wider integer, fix it by converting the void
pointer to an integer of the same size, 'unsigned long', before casting it to
'unsigned long long'.

Acked-by: Steven Rostedt <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mike Galbraith <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/traceevent/event-parse.c

···
 		 * is in the bottom half of the 32 bit field.
 		 */
 		offset &= 0xffff;
-		val = (unsigned long long)(data + offset);
+		val = (unsigned long long)((unsigned long)data + offset);
 		break;
 	default: /* not sure what to do there */
 		return 0;