drm/sun4i: dw-hdmi: always set clock rate

As expected, HDMI controller clock should always match pixel clock. In
the past, changing HDMI controller rate would seemingly worsen
situation. However, that was the result of other bugs which are now
fixed.

Fix that by removing set_rate quirk and always set clock rate.

Fixes: 40bb9d31

 ("drm/sun4i: Add support for H6 DW HDMI controller")
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Tested-by: Andre Heider <a.heider@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210209175900.7092-4-jernej.skrabec@siol.net