tracing: Fix warning on variable 'struct trace_array'

Move the declaration of 'struct trace_array' out of #ifdef
CONFIG_TRACING block, to fix the following warning when CONFIG_TRACING
is not set:

>> include/linux/trace.h:63:45: warning: 'struct trace_array' declared
inside parameter list will not be visible outside of this definition or
declaration

Link: https://lkml.kernel.org/r/20221107160556.2139463-1-shraash@google.com

Fixes: 1a77dd1c ("scsi: tracing: Fix compile error in trace_array calls when TRACING is disabled")
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Arun Easi <aeasi@marvell.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Aashish Sharma <shraash@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

include/linux/trace.h

@@ -26,13 +26,13 @@ struct trace_export {
 	int flags;
 };
 
+struct trace_array;
+
 #ifdef CONFIG_TRACING
 
 int register_ftrace_export(struct trace_export *export);
 int unregister_ftrace_export(struct trace_export *export);
 
-struct trace_array;
-
 void trace_printk_init_buffers(void);
 __printf(3, 4)
 int trace_array_printk(struct trace_array *tr, unsigned long ip,