ivi-shell: don't use input panel implementation

input panel implementation puts contents of an
application, which uses input_method protocol,
on top of all other surfaces. It is not controllable
with ivi-layout interface.

This is not acceptable for an In-Vehicle Infotainment
platform. Because we have to ensure configured scenegraph
cannot be hijacked by any rogue application.

Therefore, I am removing input panel implementation

Signed-off-by: Emre Ucan <eucan@de.adit-jv.com>