hwmon: Remove amd_energy driver

Commit 60268b0 ("hwmon: (amd_energy) modify the visibility of
the counters") restricted visibility of AMD energy counters to work
around a side-channel attack using energy data to determine which
instructions are executed. The attack is described in 'PLATYPUS:
Software-based Power Side-Channel Attacks on x86'. It relies on quick
and accurate energy readings.

This change made the counters provided by the amd_energy driver
effectively unusable for non-provileged users. However, unprivileged
read access is the whole point of hardware monitoring attributes.

An attempt to remedy the situation by limiting and randomizing access
to chip registers was rejected by AMD. Since the driver is for all
practical purposes unusable, remove it.

Cc: Naveen Krishna Chatradhi <nchatrad@amd.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -39,7 +39,6 @@ Hardware Monitoring Kernel Drivers
    adt7475
    aht10
    amc6821
-   amd_energy
    asb100
    asc7621
    aspeed-pwm-tacho

MAINTAINERS

@@ -870,13 +870,6 @@ S:	Supported
 T:	git git://people.freedesktop.org/~agd5f/linux
 F:	drivers/gpu/drm/amd/display/
 
-AMD ENERGY DRIVER
-M:	Naveen Krishna Chatradhi <nchatrad@amd.com>
-L:	linux-hwmon@vger.kernel.org
-S:	Maintained
-F:	Documentation/hwmon/amd_energy.rst
-F:	drivers/hwmon/amd_energy.c
-
 AMD FAM15H PROCESSOR POWER MONITORING DRIVER
 M:	Huang Rui <ray.huang@amd.com>
 L:	linux-hwmon@vger.kernel.org

drivers/hwmon/Kconfig

@@ -321,16 +321,6 @@ config SENSORS_FAM15H_POWER
 	  This driver can also be built as a module. If so, the module
 	  will be called fam15h_power.
 
-config SENSORS_AMD_ENERGY
-	tristate "AMD RAPL MSR based Energy driver"
-	depends on X86
-	help
-	  If you say yes here you get support for core and package energy
-	  sensors, based on RAPL MSR for AMD family 17h and above CPUs.
-
-	  This driver can also be built as a module. If so, the module
-	  will be called as amd_energy.
-
 config SENSORS_APPLESMC
 	tristate "Apple SMC (Motion sensor, light sensor, keyboard backlight)"
 	depends on INPUT && X86