net/mlx5e: Fix trust state reset in reload

Setting dscp2prio during the driver reload can cause dcb ieee app list to
be not empty after the reload finish and as a result to a conflict between
the priority trust state reported by the app and the state in the device
register.

Reset the dcb ieee app list on initialization in case this is
conflicting with the register status.

Fixes: 2a5e7a13 ("net/mlx5e: Add dcbnl dscp to priority support")
Signed-off-by: Moshe Tal <moshet@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>