linux-phytec-ti

drm/tidss: fix probe-time memleak

If tidss_modeset_init fails, which happens easily due to deferred
probing, drm_mode_config_cleanup() is not called and we leak lots of DRM
objects.

Fix this by adding the proper error handling, and for consistency, add
tidss_modeset_cleanup() which is the mirror for tidss_modeset_init().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>