vmxnet3: Move PCI Id to pci_ids.h

The VMXNet3 PCI Id will be shared with our paravirtual RDMA driver.
Moved it to the shared location in pci_ids.h.

Suggested-by: Leon Romanovsky <leon@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>