RDMA/uverbs: Fix error unwind in ib_uverbs_add_one

The error path has several mistakes

- cdev_del should not be called if cdev_device_add fails
- We must call put_device on all the goto exit paths as that is what frees
  the uapi, SRCU and the struct itself.

While we are here consolidate all the uvdev_dev init that cannot fail at
the top.

Fixes: c5c4d92e

 ("RDMA/uverbs: Use cdev_device_add() instead of cdev_add()")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>