FROMLIST: clk: rockchip: make rk3399 vop dclks keep their rate on parent rate changes

FROMLIST: clk: rockchip: make rk3399 vop dclks keep their rate on parent rate changes

The rk3399 hdmi phy is supplied by the vpll directly and needs to adapt
that frequency depending on the selected resolution on the hdmi output.
For the hdmi-phy the vpll frequency is supplied unchanged without
any dividers being present there.

The vpll also is one of the sources the general display clock of the
visual output processor (vop) and as it is somewhat special for
display operations possibly also the preferred pll source. Here a divider
is available between the pll-mux and the vop clock, so that this part
can adapt the resulting frequency if needed.

So to keep the vop clock in line with the target rate, set the newly
introduced CLK_KEEP_REQ_RATE flag for the dclk_vop clocks on rk3399.

(am from https://patchwork.kernel.org/patch/8993771/)

Change-Id: Iba9a179b764472f22d7531eb0c662dcd982433d4
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>