HID: wacom: generic: Don't sync input on empty input packets

post input_sync only when there are input events posted

Signed-off-by: Ping Cheng <ping.cheng@wacom.com>
Reviewed-By: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2 files changed