qlcnic: remove redundant D0 power state set

pci_enable_device() will set device power state to D0,
so it's no need to do it again in qlcnic_attach_func().

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>