ACPI: thinkpad-acpi: export to sysfs the state of the radio slider switch

Some ThinkPad models, notably the T60 and X60, have a slider switch to
enable and disable the radios.  The switch has the capability of
force-disabling the radios in hardware on most models, and it is supposed
to affect all radios (WLAN, WWAN, BlueTooth).

Export the switch state as a sysfs attribute, on ThinkPads where it is
available.

Thanks to Henning Schild for asking for this feature, and for tracking down
the EC register that holds the radio switch state.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Henning Schild <henning@wh9.tu-dresden.de>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/misc/thinkpad_acpi.h b/drivers/misc/thinkpad_acpi.h
index e1a64f0..78ea4c8 100644
--- a/drivers/misc/thinkpad_acpi.h
+++ b/drivers/misc/thinkpad_acpi.h
@@ -228,6 +228,7 @@
 	u16 bluetooth:1;
 	u16 hotkey:1;
 	u16 hotkey_mask:1;
+	u16 hotkey_wlsw:1;
 	u16 light:1;
 	u16 light_status:1;
 	u16 wan:1;