net/vmxnet3: add cmd to register memory region

net/vmxnet3: add cmd to register memory region

In vmxnet3 version 3, the emulation added support for the vmxnet3 driver
to communicate information about the memory regions the driver will use
for rx/tx buffers. The driver can also indicate which rx/tx queue the
memory region is applicable for. If this information is communicated
to the emulation, the emulation will always keep these memory regions
mapped, thereby avoiding the mapping/unmapping overhead for every packet.

Signed-off-by: Shrikrishna Khare <skhare@vmware.com>
Signed-off-by: Guolin Yang <gyang@vmware.com>
Acked-by: Yong Wang <yongwang@vmware.com>
Acked-by: Jin Heo <heoj@vmware.com>