HID: rmi: Scan the report descriptor to determine if the device is suitable for the hid-rmi driver

On composite HID devices there may be multiple HID devices on separate
interfaces, but hid-rmi should only bind to the touchpad. The previous version
simply checked that the interface protocol was set to mouse. Unfortuately, it
is not always the case that the touchpad has the mouse interface protocol set.
This patch takes a different approach and scans the report descriptor looking
for the Generic Desktop Pointer usage and the Vendor Specific Top Level
Collection needed by the hid-rmi driver to interface with the device.

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