ipmi: Fix compile warning with tv_usec

It's not a long int on all arches.
Signed-off-by: NCorey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_ssif.c

@@ -969,7 +969,8 @@ static void sender(void                *send_info,
 
 		do_gettimeofday(&t);
 		pr_info("**Enqueue %02x %02x: %ld.%6.6ld\n",
-		       msg->data[0], msg->data[1], t.tv_sec, t.tv_usec);
+		       msg->data[0], msg->data[1],
+		       (long) t.tv_sec, (long) t.tv_usec);
 	}
 }