ACPICA: iASL: Fix for WPBT table with no command-line arguments

Handle the case where the Command-line Arguments table field
does not exist.

ACPICA commit d6487164497fda170a1b1453c5d58f2be7c873d6

Link: acpica/acpica@d6487164
Signed-off-by: Bob Moore <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: acpibob

include/acpi/actbl3.h

@@ -723,6 +723,10 @@ struct acpi_table_wpbt {
 	u16 arguments_length;
 };
 
+struct acpi_wpbt_unicode {
+	u16 *unicode_string;
+};
+
 /*******************************************************************************
  *
  * WSMT - Windows SMM Security Mitigations Table