RDMA/efa: Remove unused 'select' field from get/set feature command descriptor

The 'select' field in the get/set feature admin command is unimplemented,
unused and misleading, remove it.  The command always refers to the
current values.

Link: https://lore.kernel.org/r/20210126120702.9807-5-galpress@amazon.com


Reviewed-by: Firas JahJah <firasj@amazon.com>
Reviewed-by: Yossi Leybovich <sleybo@amazon.com>
Signed-off-by: Gal Pressman <galpress@amazon.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>