Input: elantech - disable elan-i2c for P52 and P72

The current implementation of elan_i2c is known to not support those
2 laptops.

A proper fix is to tweak both elantech and elan_i2c to transmit the
correct information from PS/2, which would make a bad candidate for
stable.

So to give us some time for fixing the root of the problem, disable
elan_i2c for the devices we know are not behaving properly.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1803600
Link: https://bugs.archlinux.org/task/59714
Fixes: df077237

 Input: elantech - detect new ICs and setup Host Notify for them

Cc: stable@vger.kernel.org  # v4.18+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>