net/mlx5e: remove unnecessary memset

Since kvzalloc will initialize the allocated memory, it is not
necessary to initialize it once again.

Fixes: 11b717d6

 ("net/mlx5: E-Switch, Get reg_c0 value on CQE")
Signed-off-by: Zhu Yanjun <yanjunz@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>