[PATCH] hwmon: dell-smm-hwmon: fix unused variable error

[Randy Dunlap <rdunlap@infradead.org>]

When CONFIG_PROC_FS is not set, there is a build warning (turned
into an error):

../drivers/hwmon/dell-smm-hwmon.c: In function 'i8k_init_procfs':
../drivers/hwmon/dell-smm-hwmon.c:624:24: error: unused variable 'data' [-Werror=unused-variable]
  struct dell_smm_data *data = dev_get_drvdata(dev);

Fix this by making I8K depend on PROC_FS and HWMON (instead of
selecting HWMON -- we prefer and try hard not to select entire
subsystems).

Build tested in all possible combinations of SENSORS_DELL_SMM,
I8K, and PROC_FS.

Fixes: 039ae58503f3 ("hwmon: Allow to compile dell-smm-hwmon driver without /proc/i8k")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Pali Rohár <pali@kernel.org>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: linux-hwmon@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: x86@kernel.org
Cc: Armin Wolf <W_Armin@gmx.de>
---
 arch/x86/Kconfig |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- linux-next-20210910.orig/arch/x86/Kconfig
+++ linux-next-20210910/arch/x86/Kconfig
@@ -1255,7 +1255,8 @@ config TOSHIBA
 
 config I8K
 	tristate "Dell i8k legacy laptop support"
-	select HWMON
+	depends on HWMON
+	depends on PROC_FS
 	select SENSORS_DELL_SMM
 	help
 	  This option enables legacy /proc/i8k userspace interface in hwmon