Introduce an architecture function that architectures can use to set
up ("prepare") SYNC_CORE commands.
The function will be used by RISC-V to update its "deferred icache-
flush" data structures (icache_stale_mask).
Architectures defining prepare_sync_core_cmd() static inline need to
select ARCH_HAS_PREPARE_SYNC_CORE_CMD.
Signed-off-by: Andrea Parri <parri.andrea@xxxxxxxxx>
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>