net: mlx5: Use ktime_get_ns()

This code is beyond silly:

     struct timespec ts = ktime_get_ts();
     ktime_t ktime = timespec_to_ktime(ts);

Further down the code builds the delta of two ktime_t values and
converts the result to nanoseconds.

Use ktime_get_ns() and replace all the nonsense.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Eli Cohen <eli@mellanox.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

include/linux/mlx5/driver.h

@@ -604,8 +604,8 @@ struct mlx5_cmd_work_ent {
 	int			page_queue;
 	u8			status;
 	u8			token;
-	struct timespec		ts1;
-	struct timespec		ts2;
+	u64			ts1;
+	u64			ts2;
 	u16			op;
 };