tracing: Rename trace_buffer to array_buffer

As we are working to remove the generic "ring_buffer" name that is used by
both tracing and perf, the ring_buffer name for tracing will be renamed to
trace_buffer, and perf's ring buffer will be renamed to perf_buffer.

As there already exists a trace_buffer that is used by the trace_arrays, it
needs to be first renamed to array_buffer.

Link: https://lore.kernel.org/r/20191213153553.GE20583@krava

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 16fa218..bd92843 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -345,7 +345,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 	local_save_flags(irq_flags);
 	pc = preempt_count();
 
-	buffer = tr->trace_buffer.buffer;
+	buffer = tr->array_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer,
 			sys_data->enter_event->event.type, size, irq_flags, pc);
 	if (!event)
@@ -391,7 +391,7 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
 	local_save_flags(irq_flags);
 	pc = preempt_count();
 
-	buffer = tr->trace_buffer.buffer;
+	buffer = tr->array_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer,
 			sys_data->exit_event->event.type, sizeof(*entry),
 			irq_flags, pc);