pie: use U64_MAX to denote (2^64 - 1)

Use the U64_MAX macro to denote the constant (2^64 - 1).
Signed-off-by: Mohit P. Tahiliani <tahiliani@nitk.edu.in>
Signed-off-by: Leslie Monis <lesliemonis@gmail.com>
Signed-off-by: Gautam Ramakrishnan <gautamramk@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/pie.h

@@ -10,8 +10,8 @@
 
 #define QUEUE_THRESHOLD 16384
 #define DQCOUNT_INVALID -1
-#define DTIME_INVALID 0xffffffffffffffff
-#define MAX_PROB 0xffffffffffffffff
+#define DTIME_INVALID U64_MAX
+#define MAX_PROB U64_MAX
 #define PIE_SCALE 8
 
 /* parameters used */