firmware: arm_scmi: Fix missing destroy_workqueue()

destroy_workqueue is required before the return from scmi_notification_init
in case devm_kcalloc fails to allocate registered_protocols. Fix this by
simply moving registered_protocols allocation before alloc_workqueue.

Link: https://lore.kernel.org/r/20201110074221.41235-1-miaoqinglang@huawei.com


Fixes: bd31b249 ("firmware: arm_scmi: Add notification dispatch and delivery")
Suggested-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>