HID: multitouch: correct eGalax a001 protocol

This device use another protocol while sending the events.
It's the same as the one described as "serial" by Microsoft.
We are keeping here the sn_move and sn_pressure parameters for
egalax devices.

CC: Cedric Sodhi <manday@gmx.net>
CC: Chris Bagwell <chris@cnpbagwell.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-multitouch.c

@@ -97,6 +97,7 @@ struct mt_device {
 #define MT_CLS_3M				0x0101
 #define MT_CLS_CYPRESS				0x0102
 #define MT_CLS_EGALAX				0x0103
+#define MT_CLS_EGALAX_SERIAL			0x0104
 
 #define MT_DEFAULT_MAXCONTACT	10
 
@@ -174,6 +175,12 @@ struct mt_class mt_classes[] = {
 		.sn_move = 4096,
 		.sn_pressure = 32,
 	},
+	{ .name = MT_CLS_EGALAX_SERIAL,
+		.quirks =  MT_QUIRK_SLOT_IS_CONTACTID |
+			MT_QUIRK_ALWAYS_VALID,
+		.sn_move = 4096,
+		.sn_pressure = 32,
+	},
 
 	{ }
 };
@@ -705,7 +712,7 @@ static const struct hid_device_id mt_devices[] = {
 	{ .driver_data = MT_CLS_EGALAX,
 		HID_USB_DEVICE(USB_VENDOR_ID_DWAV,
 			USB_DEVICE_ID_DWAV_EGALAX_MULTITOUCH_7302) },
-	{ .driver_data = MT_CLS_EGALAX,
+	{ .driver_data = MT_CLS_EGALAX_SERIAL,
 		HID_USB_DEVICE(USB_VENDOR_ID_DWAV,
 			USB_DEVICE_ID_DWAV_EGALAX_MULTITOUCH_A001) },