net: hns3: remove unnecessary pci_set_drvdata() and devm_kfree()

There is no need for explicit calls of devm_kfree(), as the allocated
memory will be freed during driver's detach.

The driver core clears the driver data to NULL after device_release.
Thus, it is not needed to manually clear the device driver data to NULL.

So remove the unnecessary pci_set_drvdata() and devm_kfree().

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>