ACPI: DPTF: Add ACPI_DPTF Kconfig menu

Add a Kconfig menu for Intel DPTF (Dynamic Platform and Thermal
Framework), put both the existing participant drivers in it and set
them to be built as modules by default.

While at it, do a few assorted cleanups for a good measure.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Borislav Petkov <bp@suse.de>

drivers/acpi/dptf/Kconfig

 # SPDX-License-Identifier: GPL-2.0
-config DPTF_POWER
-	tristate "DPTF Platform Power Participant"
+
+menuconfig ACPI_DPTF
+	bool "Intel DPTF (Dynamic Platform and Thermal Framework) Support"
 	depends on X86
+	help
+	  Intel Dynamic Platform and Thermal Framework (DPTF) is a platform
+	  level hardware/software solution for power and thermal management.
+
+	  As a container for multiple power/thermal technologies, DPTF provides
+	  a coordinated approach for different policies to effect the hardware
+	  state of a system.
+
+	  For more information see:
+	  <https://01.org/intel%C2%AE-dynamic-platform-and-thermal-framework-dptf-chromium-os/overview>
+
+if ACPI_DPTF
+
+config DPTF_POWER
+	tristate "Platform Power DPTF Participant"
+	default m
 	help
 	  This driver adds support for Dynamic Platform and Thermal Framework
 	  (DPTF) Platform Power Participant device (INT3407) support.
@@ -16,15 +33,17 @@ config DPTF_POWER
 	  the module will be called dptf_power.
 
 config DPTF_PCH_FIVR
-	tristate "DPTF PCH FIVR Participant"
-	depends on X86
+	tristate "PCH FIVR DPTF Participant"
+	default m
 	help
 	  This driver adds support for Dynamic Platform and Thermal Framework
 	  (DPTF) PCH FIVR Participant device support. This driver allows to
-	  switch PCH FIVR (Fully Integrated Voltage Regulator) frequency.
+	  switch the PCH FIVR (Fully Integrated Voltage Regulator) frequency.
 	  This participant is responsible for exposing:
 		freq_mhz_low_clock
 		freq_mhz_high_clock
 
 	  To compile this driver as a module, choose M here:
 	  the module will be called dptf_pch_fivr.
+
+endif