PCI: Disable MSI for HiSilicon Hip06/Hip07 only in Root Port mode

HiSilicon Hip06/Hip07 can operate as either a Root Port or an Endpoint.  It
always advertises an MSI capability, but it can only generate MSIs when in
Endpoint mode.

The device has the same Vendor and Device IDs in both modes, so check the
Class Code and disable MSI only when operating as a Root Port.

[bhelgaas: changelog]
Fixes: 72f2ff0d ("PCI: Disable MSI for HiSilicon Hip06/Hip07 Root Ports")
Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Zhou Wang <wangzhou1@hisilicon.com>
Cc: stable@vger.kernel.org	# v4.11+