tracing: Fix trace_event_raw_event_synth() if else statement

The test to check if the field is a stack is to be done if it is not a
string. But the code had:

    } if (event->fields[i]->is_stack) {

and not

   } else if (event->fields[i]->is_stack) {

which would cause it to always be tested. Worse yet, this also included an
"else" statement that was only to be called if the field was not a string
and a stack, but this code allows it to be called if it was a string (and
not a stack).

Also fixed some whitespace issues.

Link: https://lore.kernel.org/all/202301302110.mEtNwkBD-lkp@intel.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230131095237.63e3ca8d@gandalf.local.home

Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 00cf3d67 ("tracing: Allow synthetic events to pass around stacktraces")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

kernel/trace/trace_events_synth.c

@@ -564,8 +564,8 @@ static notrace void trace_event_raw_event_synth(void *__data,
 					   event->fields[i]->is_dynamic,
 					   data_size, &n_u64);
 			data_size += len; /* only dynamic string increments */
-		} if (event->fields[i]->is_stack) {
-		        long *stack = (long *)(long)var_ref_vals[val_idx];
+		} else if (event->fields[i]->is_stack) {
+			long *stack = (long *)(long)var_ref_vals[val_idx];
 
 			len = trace_stack(entry, event, stack,
 					   data_size, &n_u64);