ibmvnic: Add vnic client data to login buffer

Update the login buffer to include client data for the vnic driver,
this includes the OS name, LPAR name, and device name. This update
allows this information to be available in the VIOS.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>