linux-phytec-ti

drm/radeon: move bl encoder assignment into bl init

So that the bl encoder will be null if the GPU does not
control the backlight.

Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org