firmware: arm_scmi: Use after free in scmi_create_protocol_device()

We need to return here instead of setting up the freed sdev device as a
transport.

Fixes: 907b6d14 ("firmware: arm_scmi: add per-protocol channels support using idr objects")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>