drm/sun4i: hdmi: Disable clks in bind function error path and unbind function

The HDMI driver enables the bus and mod clocks in the bind function, but
does not disable them if it then bails our due to any errors. Neither
does it disable the clocks in the unbind function.

Fix this by adding a proper error path to the bind function, and
clk_disable_unprepare calls to the unbind function.

Also rename the err_cleanup_connector label to err_cleanup_encoder,
since it is the encoder that gets cleaned up.

Fixes: 9c568101

 ("drm/sun4i: Add HDMI support")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010032008.682-4-wens@csie.org