acpi: add aml_while() term

Add encoding for ACPI DefWhile Opcode.
Reviewed-by: NShannon Zhao <zhaoshenglong@huawei.com>
Reviewed-by: NIgor Mammedov <imammedo@redhat.com>
Signed-off-by: NMarcel Apfelbaum <marcel@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

include/hw/acpi/aml-build.h

@@ -266,6 +266,7 @@ Aml *aml_device(const char *name_format, ...) GCC_FMT_ATTR(1, 2);
 Aml *aml_method(const char *name, int arg_count);
 Aml *aml_if(Aml *predicate);
 Aml *aml_else(void);
+Aml *aml_while(Aml *predicate);
 Aml *aml_package(uint8_t num_elements);
 Aml *aml_buffer(int buffer_size, uint8_t *byte_list);
 Aml *aml_resource_template(void);