Send the native scancode in evdevkeyboard

Send the native scancode in evdevkeyboard

Until now the native scancode was not specified which meant
when qwindow-compositor (or any other Qt-based compositor using
the standard Wayland protocol, i.e. sendKeyPress() and such) tried
to send the native scancode over to the clients, all it got was a
code of 0.

This fixes keyboard input when running qwindow-compositor on top
of kms and EvdevKeyboard.

Change-Id: I5d9a882f249634fb7584900b5f298f794befee3b
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>