net/mlx5e: Use memset to init skbs_frags array to zeros

In RX data-path, use memset() instead of loop assignment
to init the whole skbs_frags array.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>