net/mlx5: Clear health sick bit when starting health poll

The health sick status should be cleared when we start the health poll.
This is crucial for driver reload (unload + load) in order to behave
right in case of health issue.

Fixes: fd76ee4d ('net/mlx5_core: Fix internal error detection conditions')
Signed-off-by: Mohamad Haj Yahia <mohamad@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>