Configure the transcoder to operate in TE GATE command mode
and  take TE events from GPIO.
Also disable the periodic command mode, that GOP would have
programmed.

v2: Disable util pin (Jani)
v3: Use intel_de_write (Jani)
Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200312053841.2794-2-vandita.kulkarni@intel.com