firmware: arm_scmi: Cleanup legacy protocol init code

Now that all protocols and drivers have been ported to the new interface
based on protocol handles and get/put operations, remove all the legacy
transient initialization code.

Link: https://lore.kernel.org/r/20210316124903.35011-33-cristian.marussi@arm.com


Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>