composior: fix tiny cursor bug with drm compositor

composior: fix tiny cursor bug with drm compositor

The drm compositor always creates a 64x64 bo for the cursor image
regardless of the size of the actual cursor. When the fade animation
kicks in it disables the hardware cursor so that it is rendered as a
regular surface. This surface is rendered to a 32x32 region but using
a 64x64 texture so the cursor gets scaled down.

Fix this by making create_cursor_image return the actual size of the
image created to the compositor.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>