x86/Kconfig: move and modify CONFIG_I8K

In Kconfig, inside the "Processor type and features" menu, there is
the CONFIG_I8K option: "Dell i8k legacy laptop support". This is
very confusing - enabling CONFIG_I8K is not required for the kernel to
support old Dell laptops. This option is specific to the dell-smm-hwmon
driver, which mostly exports some hardware monitoring information and
allows the user to change fan speed.

This option is misplaced, so move CONFIG_I8K to drivers/hwmon/Kconfig,
where it belongs.

Also, modify the dependency order - change
        select SENSORS_DELL_SMM
to
        depends on SENSORS_DELL_SMM
as it is just a configuration option of dell-smm-hwmon. This includes
changing the option type from tristate to bool. It was tristate because
it could select CONFIG_SENSORS_DELL_SMM=m .

When running "make oldconfig" on configurations with
CONFIG_SENSORS_DELL_SMM enabled , this change will result in an
additional question (which could be printed several times during
bisecting). I think that tidying up the configuration is worth it,
though.

Next patch tweaks the description of CONFIG_I8K.

Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Cc: Pali Rohár <pali@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Mark Gross <markgross@kernel.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220212125654.357408-1-mat.jonczyk@o2.pl


Signed-off-by: Guenter Roeck <linux@roeck-us.net>