gma tgl: Fill out power and clocks module

This is the modeset sequence for the display engine itself.  TGL has
similarities to both SKL and BXT, but also adds new programming, like
MBUS credits, Bandwidth Buddy, and of course new chicken bits.

Tested on google/delbin; can still boot successfully to the kernel and
the kernel can still properly perform its own modeset and not crash :)

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Change-Id: I8f09696588aa73cebc7a44583ae5e029c705a535
Reviewed-on: https://review.sourcearcade.org/c/libgfxinit/+/464
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: Nico Huber <nico.h@gmx.de>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index 9c150c4..7867268 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -385,7 +385,7 @@
       elsif Gen_Haswell                      then 450_000_000
       elsif Gen_Broxton                      then 288_000_000
       elsif Gen_Skylake                      then 337_500_000
-      elsif Gen_Tigerlake                    then CDClk_Range'First  -- depends on ref clk
+      elsif Gen_Tigerlake                    then 172_800_000  -- depends on ref clk
                                              else CDClk_Range'First);
 
    Default_RawClk_Freq : <hswvar> Frequency_Type :=