drm: handle cursor_set2 in restore_fbdev_mode

If a driver uses the cursor_set2 crtc callback rather than
cursor_set, use that.  This fixes the fbdev helper for drivers
that use cursor_set2.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>