firmware: arm_scmi: Add clock .state_get support to pre-v3.2

firmware: arm_scmi: Add clock .state_get support to pre-v3.2

Support clock .state_get operation against SCMI platform servers that do
not support v3.2 CONFIG_GET dedicated command: while talking with these
platforms the command CLOCK_ATTRIBUTES can be used to gather the current
clock states.

Note that, in case of shared resources, the retrieved clock state 'flavour'
(virtual vs physical) depends on the backend SCMI platform server specific
kind of implementation.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230826125308.462328-5-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>