qed: fix invalid use of sizeof in qed_alloc_qm_data()

sizeof() when applied to a pointer typed expression gives the
size of the pointer, not that of the pointed data.

Fixes: b5a9ee7c

 ("qed: Revise QM configuration")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>