drm/vc4: hdmi: Fix error path of hpd-gpios

If the of_get_named_gpio_flags call fails in vc4_hdmi_bind, we jump to
the err_unprepare_hsm label. That label will then call
pm_runtime_disable and put_device on the DDC device.

We just retrieved the DDC device, so the latter is definitely justified.
However at that point we still haven't called pm_runtime_enable, so the
call to pm_runtime_disable is not supposed to be there.

Fixes: 10ee275c ("drm/vc4: prepare for CEC support")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210524131852.263883-1-maxime@cerno.tech