char: lack of bool string made CONFIG_DEVPORT always on

commit f2cfa58b upstream.

Without a bool string present, using "# CONFIG_DEVPORT is not set" in
defconfig files would not actually unset devport. This esnured that
/dev/port was always on, but there are reasons a user may wish to
disable it (smaller kernel, attack surface reduction) if it's not being
used. Adding a message here in order to make this user visible.
Signed-off-by: Max Bires <jbires@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

drivers/char/Kconfig

@@ -567,9 +567,12 @@ config TELCLOCK
 	  controlling the behavior of this hardware.
 
 config DEVPORT
-	bool
+	bool "/dev/port character device"
 	depends on ISA || PCI
 	default y
+	help
+	  Say Y here if you want to support the /dev/port device. The /dev/port
+	  device is similar to /dev/mem, but for I/O ports.
 
 source "drivers/s390/char/Kconfig"