ACPICA: Permanently set _REV to the value '2'.

ACPICA commit 7af00219681ab35ebe57d64a9189fd04a5a026d8

Windows uses a value of 2, and has no plans to ever change this. So, _REV is
essentially useless for its primary purpose.

Worse, some BIOS vendors have used the difference in _REV values between
Windows and ACPICA to indicate which one is running.

It has been decided by the ACPI community to deprecate this method, and return
1 for ACPI 1.0 (32-bit integers) and 2 for ACPI 2.0 and greater (both 32-bit
and 64-bit integers.

ACPICA is changed to reflect this.

Link: https://github.com/acpica/acpica/commit/7af00219
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/utglobal.c

@@ -102,12 +102,19 @@ const struct acpi_predefined_names acpi_gbl_pre_defined_names[] = {
 	{"_SB_", ACPI_TYPE_DEVICE, NULL},
 	{"_SI_", ACPI_TYPE_LOCAL_SCOPE, NULL},
 	{"_TZ_", ACPI_TYPE_DEVICE, NULL},
-	{"_REV", ACPI_TYPE_INTEGER, (char *)ACPI_CA_SUPPORT_LEVEL},
+	/*
+	 * March, 2015:
+	 * The _REV object is in the process of being deprecated, because
+	 * other ACPI implementations permanently return 2. Thus, it
+	 * has little or no value. Return 2 for compatibility with
+	 * other ACPI implementations.
+	 */
+	{"_REV", ACPI_TYPE_INTEGER, ACPI_CAST_PTR(char, 2)},
 	{"_OS_", ACPI_TYPE_STRING, ACPI_OS_NAME},
-	{"_GL_", ACPI_TYPE_MUTEX, (char *)1},
+	{"_GL_", ACPI_TYPE_MUTEX, ACPI_CAST_PTR(char, 1)},
 
 #if !defined (ACPI_NO_METHOD_EXECUTION) || defined (ACPI_CONSTANT_EVAL_ONLY)
-	{"_OSI", ACPI_TYPE_METHOD, (char *)1},
+	{"_OSI", ACPI_TYPE_METHOD, ACPI_CAST_PTR(char, 1)},
 #endif
 
 	/* Table terminator */