Remove redundant double casts in time functions

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/time.c b/time.c
index 108c0fc..c6a6287 100644
--- a/time.c
+++ b/time.c
@@ -17,7 +17,7 @@
 		usec += 1000000;
 	}
 
-	sec *= (double) 1000000;
+	sec *= 1000000UL;
 
 	return sec + usec;
 }
@@ -41,8 +41,8 @@
 		usec += 1000000;
 	}
 
-	sec *= (double) 1000;
-	usec /= (double) 1000;
+	sec *= 1000UL;
+	usec /= 1000UL;
 
 	return sec + usec;
 }