ktime: Use macro NSEC_PER_USEC where appropriate

We've got the macro NSEC_PER_USEC defined in header file
include/linux/time.h. To make the code decent, this patch
replaces the immediate number 1000 to convert bewteen a
time value in microseconds and one in nanoseconds with the
macro NSEC_PER_USEC.
Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

include/linux/ktime.h

@@ -229,7 +229,8 @@ static inline ktime_t timespec_to_ktime(const struct timespec ts)
 static inline ktime_t timeval_to_ktime(const struct timeval tv)
 {
 	return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
-				   .nsec = (s32)tv.tv_usec * 1000 } };
+				   .nsec = (s32)(tv.tv_usec *
+						 NSEC_PER_USEC) } };
 }
 
 /**
@@ -320,12 +321,12 @@ static inline s64 ktime_us_delta(const ktime_t later, const ktime_t earlier)
 
 static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
 {
-	return ktime_add_ns(kt, usec * 1000);
+	return ktime_add_ns(kt, usec * NSEC_PER_USEC);
 }
 
 static inline ktime_t ktime_sub_us(const ktime_t kt, const u64 usec)
 {
-	return ktime_sub_ns(kt, usec * 1000);
+	return ktime_sub_ns(kt, usec * NSEC_PER_USEC);
 }
 
 extern ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs);