s390/qeth: add basic VNICC support

VNIC Characteristics (VNICC) are features of HiperSockets that define
how packets are handled by the underlying network hardware. For example,
if the VNICC flooding is configured on a qeth device, ethernet frames to
unknown destination MAC addresses are received.

Currently, there is support for seven VNICCs: flooding, multicast
flooding, receive broadcast, learning, takeover learning, takeover
setvmac, bridge invisible. Also, six IPA commands exist for configuring
VNICCs on a qeth device: query characteristics, query commands, enable
characteristic, disable characteristic, set timeout, get timeout.

This patch adds the basic code infrastructure for VNICC support to qeth.
It allows querying VNICC support from the underlying hardware. To this
end, it adds:

* basic message formats for IPA commands
* basic data structures
* basic error handling
* query characteristics IPA command support

The query characteristics IPA command allows requesting the currently
supported and currently enabled VNIC characteristics from the underlying
hardware.

Support for the other IPA commands and for the configuration of VNICCs
is added in follow-up patches together with the respective user
interface functions.

Signed-off-by: Hans Wippel <hwippel@linux.vnet.ibm.com>
Reviewed-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>