drm/vc4: hdmi: Fix HPD GPIO error path

The HPD GPIO retrieval code on failure will jump to the
err_unprepare_hsm label that calls pm_runtime_disable.

However at that point we haven't called pm_runtime_enable, so we end up
with an unbalanced call.

The next error than can occur (and therefore the next label) needs both
pm_runtime_disable and drm_encoder_cleanup though, so let's rearrange
the labels to match what we expect.

Fixes: cd4cb49d

 ("drm/vc4: hdmi: Adjust HSM clock rate depending on pixel rate")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>