Input: wacom - add serial number for Graphire4 and old Bamboo

With the removal of BTN_TOOL_FINGER for tablet buttons and
expresskeys, serial number is needed to distingush if the
events were from a regular tool (stylus, eraser, or mouse)
or the attribures (buttons, strips, or wheels) on the tablet
since there are overlapped events between the tools and the
tablet attributes.

Signed-off-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Chris Bagwell <chris@cnpbagwell.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/tablet/wacom_wac.c

@@ -265,6 +265,7 @@ static int wacom_graphire_irq(struct wacom_wac *wacom)
 			wacom->id[0] = 0;
 		input_report_abs(input, ABS_MISC, wacom->id[0]); /* report tool id */
 		input_report_key(input, wacom->tool[0], prox);
+		input_event(input, EV_MSC, MSC_SERIAL, 1);
 		input_sync(input); /* sync last event */
 	}