drm/tilcdc: Fix the error path in tilcdc_load()

The current error path calls tilcdc_unload() in case of an error to release
the resources. However, this is wrong because not all resources have been
allocated by the time an error occurs in tilcdc_load().

To fix it, this commit adds proper labels to bail out at the different
stages in the load function, and release only the resources actually allocated.

Tested-by: Darren Etheridge <detheridge@ti.com>
Tested-by: Johannes Pointner <johannes.pointner@br-automation.com>
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Dave Airlie <airlied@redhat.com>