eglfs: implement hardware cursor for the raspberry-pi

eglfs: implement hardware cursor for the raspberry-pi

The cursor is rendered on a dispmanx layer and moved
around. This approach saves us from having to update the
underlying window each time the cursor moves.

Dispmanx layers cannot be moved to negative coords. As
a result, currently it is not possible to move to a
location less than the hostpot. A future commit will
fix this problem.

Change-Id: Ida5ee961d03a6929860c515e503482756a4913ed
Reviewed-by: Johannes Zellner <johannes.zellner@nokia.com>
Reviewed-by: Andy Nichols <andy.nichols@nokia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>