fs: preserve nanosecond resolution in uv__fs_to_timespec

Remove microsecond truncation to utilize full nanosecond resolution
supported by utimesat().

src/unix/fs.c

@@ -224,13 +224,6 @@ static struct timespec uv__fs_to_timespec(double time) {
   ts.tv_sec  = time;
   ts.tv_nsec = (time - ts.tv_sec) * 1e9;
 
- /* TODO(bnoordhuis) Remove this. utimesat() has nanosecond resolution but we
-  * stick to microsecond resolution for the sake of consistency with other
-  * platforms. I'm the original author of this compatibility hack but I'm
-  * less convinced it's useful nowadays.
-  */
-  ts.tv_nsec -= ts.tv_nsec % 1000;
-
   if (ts.tv_nsec < 0) {
     ts.tv_nsec += 1e9;
     ts.tv_sec -= 1;