ipmi: Fix pr_fmt to avoid compilation issues

The was it was wouldn't work in some situations, simplify it.  What was
there was unnecessary complexity.
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NCorey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_msghandler.c

@@ -11,8 +11,8 @@
  * Copyright 2002 MontaVista Software Inc.
  */
 
-#define pr_fmt(fmt) "%s" fmt, "IPMI message handler: "
-#define dev_fmt pr_fmt
+#define pr_fmt(fmt) "IPMI message handler: " fmt
+#define dev_fmt(fmt) pr_fmt(fmt)
 
 #include <linux/module.h>
 #include <linux/errno.h>