arch: support customized up_cpu_index() in AMP mode

Some app with same code runs on different cores in AMP mode,
need the physical core on which the function is called.

Signed-off-by: hujun5 <hujun5@xiaomi.com>
Signed-off-by: fangxinyong <fangxinyong@xiaomi.com>

drivers/syslog/vsyslog.c

@@ -215,7 +215,7 @@ int nx_vsyslog(int priority, FAR const IPTR char *fmt, FAR va_list *ap)
 #endif
 
 #if defined(CONFIG_SMP)
-                             , up_cpu_index()
+                             , this_cpu()
 #endif
 
 #if defined(CONFIG_SYSLOG_PROCESSID)