clk: sunxi-ng: h3: h5: export CLK_PLL_VIDEO

CLK_PLL_VIDEO needs to be referenced in HDMI DT entry as a possible
PHY clock parent.

Export it so it can be used later in DT.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>