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

Revert commit b1ef297 (ACPICA: Permanently set _REV to the value
'2'.) as it causes a sound regression to happen on Dell XPS 13 (2015).

Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/utglobal.c

@@ -102,19 +102,12 @@ 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},
-	/*
-	 * 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)},
+	{"_REV", ACPI_TYPE_INTEGER, (char *)ACPI_CA_SUPPORT_LEVEL},
 	{"_OS_", ACPI_TYPE_STRING, ACPI_OS_NAME},
-	{"_GL_", ACPI_TYPE_MUTEX, ACPI_CAST_PTR(char, 1)},
+	{"_GL_", ACPI_TYPE_MUTEX, (char *)1},
 
 #if !defined (ACPI_NO_METHOD_EXECUTION) || defined (ACPI_CONSTANT_EVAL_ONLY)
-	{"_OSI", ACPI_TYPE_METHOD, ACPI_CAST_PTR(char, 1)},
+	{"_OSI", ACPI_TYPE_METHOD, (char *)1},
 #endif
 
 	/* Table terminator */