IB/uverbs: Add IDRs array attribute type to ioctl() interface

Methods sometimes need to get a flexible set of IDRs and not a strict set
as can be achieved today by the conventional IDR attribute. Add a new
IDRS_ARRAY attribute to the generic uverbs ioctl layer.

IDRS_ARRAY points to array of idrs of the same object type and same access
rights, only write and read are supported.

Signed-off-by: Guy Levi <guyle@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com&gt;``>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>