PCI: pnv_php: Use kmemdup()

Use kmemdup() rather than duplicating its implementation.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>