HID: multitouch: fix Elan panels with 2 input modes declaration

When implementing commit 7f81c8db ("HID: multitouch: simplify
the settings of the various features"), I wrongly removed a test
that made sure we never try to set the second InputMode feature
to something else than 0.

This broke badly some recent Elan panels that now forget to send the
click button in some area of the touchpad.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200899


Fixes: 7f81c8db ("HID: multitouch: simplify the settings of the various features")
Cc: stable@vger.kernel.org # v4.18+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>