firmware: arm_scmi: Add standard clock OEM definitions

Add a common enum to define the standard clock OEM types defined by the
SCMI specification, so as to enable the configuration of such extended
configuration properties with the existent clock protocol operations.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20240214183006.3403207-5-cristian.marussi@arm.com


Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>