The device .release function was not being set during the device
initialization. This was leading to the below warning, in error cases when
put_srv was called before device_add was called.

Warning:

Device '(null)' does not have a release() function, it is broken and must
be fixed. See Documentation/kobject.txt.

So, set the device .release function during device initialization in the
__alloc_srv() function.

Fixes: baa5b28b ("RDMA/rtrs-srv: Replace device_register with device_initialize and device_add")
Link: https://lore.kernel.org/r/20200907102216.104041-1-haris.iqbal@cloud.ionos.comSigned-off-by: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>