staging: dwc2: 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 dwc2_driver_probe().

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>