Input: elantech - remove P52 and P72 from SMBus blacklist

Both now works correctly over SMBus. Let's use this driver so we can
update all five fingers every 8ms.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>