ACPI: fix "acpi=ht" boot option

We broke "acpi=ht" in 2.6.32 by disabling MADT parsing
for acpi=disabled.  e5b8fc6ac158f65598f58dba2c0d52ba3b412f52
This also broke systems which invoked acpi=ht via DMI blacklist.

acpi=ht is a really ugly hack,
but restore it for those that still use it.

http://bugzilla.kernel.org/show_bug.cgi?id=14886

Signed-off-by: Len Brown <len.brown@intel.com>

arch/ia64/include/asm/acpi.h

@@ -94,6 +94,7 @@ ia64_acpi_release_global_lock (unsigned int *lock)
 #define acpi_noirq 0	/* ACPI always enabled on IA64 */
 #define acpi_pci_disabled 0 /* ACPI PCI always enabled on IA64 */
 #define acpi_strict 1	/* no ACPI spec workarounds on IA64 */
+#define acpi_ht 0	/* no HT-only mode on IA64 */
 #endif
 #define acpi_processor_cstate_check(x) (x) /* no idle limits on IA64 :) */
 static inline void disable_acpi(void) { }

drivers/acpi/tables.c

@@ -213,7 +213,7 @@ acpi_table_parse_entries(char *id,
 	unsigned long table_end;
 	acpi_size tbl_size;
 
-	if (acpi_disabled)
+	if (acpi_disabled && !acpi_ht)
 		return -ENODEV;
 
 	if (!handler)
@@ -280,7 +280,7 @@ int __init acpi_table_parse(char *id, acpi_table_handler handler)
 	struct acpi_table_header *table = NULL;
 	acpi_size tbl_size;
 
-	if (acpi_disabled)
+	if (acpi_disabled && !acpi_ht)
 		return -ENODEV;
 
 	if (!handler)