HID: multitouch: make MT_CLS_ALWAYS_TRUE the new default class

By running a test on all the traces of the devices I have,
I noticed that the class MT_CLS_ALWAYS_TRUE could handle all
the devices I've seen so far without any other quirks.
I guess this is the behavior Win 7 requires in its driver.

We can change the default class then and keep the existing classes
for backward compatibility and performances for some of them.

Two operations have been done:
 * replaced MT_CLS_DEFAULT by MT_CLS_NSMU
 * then replaced MT_CLS_ALWAYS_TRUE by MT_CLS_DEFAULT

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