It appears that there is a typo in the rk3288 TRM.  For
GRF_SOC_CON0[7] it says that 0 means "vepu" and 1 means "vdpu".  It's
the other way around.

How do I know?  Here's my evidence:

1. Prior to commit 4d3e84f9 ("clk: rockchip: describe aclk_vcodec
   using the new muxgrf type on rk3288") we always pretended that we
   were using "aclk_vdpu" and the comment in the code said that this
   matched the default setting in the system.  In fact the default
   setting is 0 according to the TRM and according to reading memory
   at bootup.  In addition rk3288-based Chromebooks ran like this and
   the video codecs worked.
2. With the existing clock code if you boot up and try to enable the
   new VIDEO_ROCKCHIP_VPU as a module (and without "clk_ignore_unused"
   on the command line), you get errors like "failed to get ack on
   domain 'pd_video', val=0x80208".  After flipping vepu/vdpu things
   init OK.
3. If I export and add both the vepu and vdpu to the list of clocks
   for RK3288_PD_VIDEO I can get past the power domain errors, but now
   I freeze when the vpu_mmu gets initted.
4. If I just mark the "vdpu" as IGNORE_UNUSED then everything boots up
   and probes OK showing that somehow the "vdpu" was important to keep
   enabled.  This is because we were actually using it as a parent.
5. After this change I can hack "aclk_vcodec_pre" to parent from
   "aclk_vepu" using assigned-clocks and the video codec still probes
   OK.
6. Rockchip has said so on the mailing list [1].

...so let's fix it.

Let's also add CLK_SET_RATE_PARENT to "aclk_vcodec_pre" as suggested
by Jonas Karlman.  Prior to the same commit you could do
clk_set_rate() on "aclk_vcodec" and it would change "aclk_vdpu".
That's because "aclk_vcodec" was a simple gate clock (always gets
CLK_SET_RATE_PARENT) and its direct parent was "aclk_vdpu".  After
that commit "aclk_vcodec_pre" gets in the way so we need to add
CLK_SET_RATE_PARENT to it too.

[1] https://lkml.kernel.org/r/1d17b015-9e17-34b9-baf8-c285dc1957aa@rock-chips.com

Fixes: 4d3e84f9 ("clk: rockchip: describe aclk_vcodec using the new muxgrf type on rk3288")
Suggested-by: Jonas Karlman <jonas@kwiboo.se>
Suggested-by: Randy Li <ayaka@soulik.info>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>