Revert "HID: logitech-hidpp: support combo keyboard touchpad TK820"

This reverts commit 3a61e975

.

The Logitech TK820 seems to be affected by a firmware bug which
delays the sending of the keys (pressed, or released, which triggers
a key-repeat) while holding fingers on the touch sensor.
This behavior can be observed while using the mouse emulation mode
if the user moves the finger while typing (highly improbable though).
Holding the finger still while in the mouse emulation mode does
not trigger the key repeat problem.
So better keep things in their previous state to not have to
explain users that the new key-repeat bug they see is a "feature".

Furthermore, I noticed that I disabled the media keys whith
this patch. Sorry, my bad.

I think it is best to revert the patch, in all the current
versions it has been shipped.

Cc: <stable@vger.kernel.org> # v3.19 and above
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>