net/mlx5e: Fix wrong delay calculation for overflow check scheduling

The overflow_period is calculated in seconds. In order to use it
for delayed work scheduling translation to jiffies is needed.

Fixes: ef9814de ('net/mlx5e: Add HW timestamping (TS) support')
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>