drm/omap: hdmi4: fix use of uninitialized var

If use_mclk is false, mclk_mode is written to a register without
initialization. This doesn't cause any ill effects as the written value
is not used when use_mclk is false.

To fix this, write use_mclk only when use_mclk is true.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190930103840.18970-8-tomi.valkeinen@ti.com


Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>