IB/uverbs: Extend uverbs_ioctl header with driver_id

Extending uverbs_ioctl header with driver_id and another reserved
field. driver_id should be used in order to identify the driver.
Since every driver could have its own parsing tree, this is necessary
for strace support.
Downstream patches take off the EXPERIMENTAL flag from the ioctl() IB
support and thus we add some reserved fields for future usage.

Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>