hwmon: Allow to compile dell-smm-hwmon driver without /proc/i8k

This patch splits CONFIG_I8K compile option to SENSORS_DELL_SMM and CONFIG_I8K.
Option SENSORS_DELL_SMM is now used to enable compilation of dell-smm-hwmon
driver and old CONFIG_I8K option to enable /proc/i8k interface in driver.

So this change allows to compile dell-smm-hwmon driver without legacy /proc/i8k
interface which is needed only for old Dell Inspirion models or for userspace
i8kutils package.

For backward compatibility when CONFIG_I8K is enabled then also SENSORS_DELL_SMM
is enabled and so driver dell-smm-hwmon (with /proc/i8k) is compiled.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 25d9e72..bc9d90b1 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -371,6 +371,17 @@
 	  This driver can also be built as a module.  If so, the module
 	  will be called ds1621.
 
+config SENSORS_DELL_SMM
+	tristate "Dell laptop SMM BIOS hwmon driver"
+	depends on X86
+	help
+	  This hwmon driver adds support for reporting temperature of different
+	  sensors and controls the fans on Dell laptops via System Management
+	  Mode provided by Dell BIOS.
+
+	  When option I8K is also enabled this driver provides legacy /proc/i8k
+	  userspace interface for i8kutils package.
+
 config SENSORS_DA9052_ADC
 	tristate "Dialog DA9052/DA9053 ADC"
 	depends on PMIC_DA9052