IB/core: Add idr based standard types

This patch adds the standard idr based types. These types are
used in downstream patches in order to initialize, destroy and
lookup IB standard objects which are based on idr objects.

An idr object requires filling out several parameters. Its op pointer
should point to uverbs_idr_ops and its size should be at least the
size of ib_uobject. We add a macro to make the type declaration easier.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>