HID: multitouch: Add support for button type usage

According to [1], Windows Precision Touchpad devices must supply
a button type usage in the device capabilities feature report. A
value of 0 indicates that the device contains a depressible
button (i.e. it's a click-pad) whereas a value of 1 indicates
a non-depressible button. Add support for this usage and set
INPUT_PROP_BUTTONPAD on the touchpad input device whenever a
depressible button is present.

[1] https://msdn.microsoft.com/en-us/library/windows/hardware/dn467314(v=vs.85).aspx

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 8bf61d2..4b2a18a 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -165,6 +165,7 @@
     {0, 0x53, "DeviceIndex"},
     {0, 0x54, "ContactCount"},
     {0, 0x55, "ContactMaximumNumber"},
+    {0, 0x59, "ButtonType"},
     {0, 0x5A, "SecondaryBarrelSwitch"},
     {0, 0x5B, "TransducerSerialNumber"},
   { 15, 0, "PhysicalInterfaceDevice" },