net: qlcnic: delete redundant memsets

In all cases, mbx->req.arg and mbx->rsp.arg have just been allocated
using kcalloc(), so these six memsets are redundant.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>