firmware: arm_scmi: Move errors defs and code to common.h

Move SCMI error codes definitions and helper to the common.h header
together with the delayed response timeout define.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-7-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>