HID: wacom: correct misreported EKR ring values

commit fcf887e7 upstream.

The EKR ring claims a range of 0 to 71 but actually reports
values 1 to 72. The ring is used in relative mode so this
change should not affect users.
Signed-off-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
Fixes: 72b236d6 ("HID: wacom: Add support for Express Key Remote.")
Cc: <stable@vger.kernel.org> # v4.3+
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Reviewed-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hid/wacom_wac.c

@@ -1061,7 +1061,7 @@ static int wacom_remote_irq(struct wacom_wac *wacom_wac, size_t len)
 	input_report_key(input, BTN_BASE2, (data[11] & 0x02));
 
 	if (data[12] & 0x80)
-		input_report_abs(input, ABS_WHEEL, (data[12] & 0x7f));
+		input_report_abs(input, ABS_WHEEL, (data[12] & 0x7f) - 1);
 	else
 		input_report_abs(input, ABS_WHEEL, 0);