HID: multitouch: make use of HID_QUIRK_INPUT_PER_APP

We now have HID_QUIRK_INPUT_PER_APPLICATION that splits the devices
into several devices. This helps us as we can now rely on hid-input
to set the names for us.

Also, this helps removing some magical numbers '0' when calling
.input_configured().

The only thing to take care of is that the field .report in struct
hid_input is now null. We need to iterate over the full list of
reports attached to a hid_input.

This is required for some Advanced Silicon touchscreen to correctly apply
the HID_QUIRK_INPUT_PER_APPLICATION as they have 2 reports associated
with the hidinput node. One contains the Input data, the other one
contains the Output data.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>