forked from Mirrors/opensbi

sbi_ipi_event_create() disallows registering an IPI event with a NULL .process callback, so the function pointer will never be NULL here. Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Reviewed-by: Anup Patel <anup@brainfault.org> Reviewed-by: Xiang W <wxjstz@126.com>