The automatic object lifetime model allows us to change the write()
interface to have the same logic as the ioctl() path. Update the
create/alloc functions to be in the following format, so the code flow
will be the same:

 * Allocate objects
 * Initialize them
 * Call to the drivers, this is last step that is allowed to fail
 * Finalize object
 * Return response and allow to core code to handle abort/commit
   respectively.

Link: https://lore.kernel.org/r/20200719052223.75245-3-leon@kernel.orgSigned-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>