net/mlx5: Use del_timer_sync in fw reset flow of halting poll

Substitute del_timer() with del_timer_sync() in fw reset polling
deactivation flow, in order to prevent a race condition which occurs
when del_timer() is called and timer is deactivated while another
process is handling the timer interrupt. A situation that led to
the following call trace:
	RIP: 0010:run_timer_softirq+0x137/0x420
	<IRQ>
	recalibrate_cpu_khz+0x10/0x10
	ktime_get+0x3e/0xa0
	? sched_clock_cpu+0xb/0xc0
	__do_softirq+0xf5/0x2ea
	irq_exit_rcu+0xc1/0xf0
	sysvec_apic_timer_interrupt+0x9e/0xc0
	asm_sysvec_apic_timer_interrupt+0x12/0x20
	</IRQ>

Fixes: 38b9f903 ("net/mlx5: Handle sync reset request event")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c

@@ -132,7 +132,7 @@ static void mlx5_stop_sync_reset_poll(struct mlx5_core_dev *dev)
 {
 	struct mlx5_fw_reset *fw_reset = dev->priv.fw_reset;
 
-	del_timer(&fw_reset->timer);
+	del_timer_sync(&fw_reset->timer);
 }
 
 static void mlx5_sync_reset_clear_reset_requested(struct mlx5_core_dev *dev, bool poll_health)