module/scmi: Handle unsupported SCMI message
In the SCMI handler table, unsupported messages are indicated by leaving the corresponding function pointer unassigned. However, there is no validation check on entry which leads to potential null pointer dereference while handling message. This change explicitly initializes the handler table and validates entry in runtime to determine whether a given message is supported.
Signed-off-by: Wei-Chia Su Wei-Chia.Su@arm.com