Input: ALPS - detect trackstick presence for v7 protocol

This patch adds detection of trackstick for v7 protocol devices. Code in
this patch is used in official Dell touchpad linux drivers for Dell models:
Dell Latitude E5250/5250, E5450/5450, E5550/5550

Detection code and base reg for alps v3 rushmore and v7 devices is exacly
same.

Also user in bug https://bugzilla.kernel.org/show_bug.cgi?id=94801

 reported
that Toshiba Sattellite Z30-A-1DG has only alps v7 touchpad device without
trackstick and kernel reports to userspace also redundant trackstick
device.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Alex Hung <alex.hung@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>