ACPI / tables: add DSDT AmlCode new declaration name support

A new naming rule was added in ACPICA version 20180427 changing
the DSDT AML code name from "AmlCode" to "dsdt_aml_code".

That change was made by commit 83b2fa943b "ACPICA: iASL: Enhance
the -tc option (create AML hex file in C)".

Tested:
ACPICA release version 20180427+.
ARM64: QCOM QDF2400
GCC: 4.8.5 20150623

Signed-off-by: Wang Dongsheng <dongsheng.wang@hxt-semitech.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/Kconfig

@@ -336,7 +336,7 @@ config ACPI_CUSTOM_DSDT_FILE
 	  See Documentation/acpi/dsdt-override.txt
 
 	  Enter the full path name to the file which includes the AmlCode
-	  declaration.
+	  or dsdt_aml_code declaration.
 
 	  If unsure, don't enter a file name.
 

drivers/acpi/tables.c

@@ -712,6 +712,9 @@ acpi_os_physical_table_override(struct acpi_table_header *existing_table,
 					  table_length);
 }
 
+static void *amlcode __attribute__ ((weakref("AmlCode")));
+static void *dsdt_amlcode __attribute__ ((weakref("dsdt_aml_code")));
+
 acpi_status
 acpi_os_table_override(struct acpi_table_header *existing_table,
 		       struct acpi_table_header **new_table)
@@ -722,8 +725,11 @@ acpi_os_table_override(struct acpi_table_header *existing_table,
 	*new_table = NULL;
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
-	if (strncmp(existing_table->signature, "DSDT", 4) == 0)
-		*new_table = (struct acpi_table_header *)AmlCode;
+	if (!strncmp(existing_table->signature, "DSDT", 4)) {
+		*new_table = (struct acpi_table_header *)&amlcode;
+		if (!(*new_table))
+			*new_table = (struct acpi_table_header *)&dsdt_amlcode;
+	}
 #endif
 	if (*new_table != NULL)
 		acpi_table_taint(existing_table);