RDMA/efa: Store network attributes in device attributes

RDMA/efa: Store network attributes in device attributes

There's no reason to separate the network attributes from all other
device attributes. Embed the fields inside the device attributes and
query them all in one function.

Link: https://lore.kernel.org/r/20191121141509.59297-2-galpress@amazon.com
Reviewed-by: Daniel Kranzdorf <dkkranzd@amazon.com>
Reviewed-by: Yossi Leybovich <sleybo@amazon.com>
Signed-off-by: Gal Pressman <galpress@amazon.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>