gfx: Increase range of Frequency_Type

New range limits are the minimum and maximum CDClk for Broxton.

Change-Id: I55a77b73ffef90eb08551c49978d020b1cf7eecc
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/26841
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/hw-gfx.ads b/common/hw-gfx.ads
index a6c883e..86ef51b 100644
--- a/common/hw-gfx.ads
+++ b/common/hw-gfx.ads
@@ -63,7 +63,7 @@
       Rotation => No_Rotation,
       Offset   => 0);
 
-   subtype Frequency_Type is Pos64 range 24_000_000 .. 600_000_000;
+   subtype Frequency_Type is Pos64 range 19_200_000 .. 624_000_000;
 
    type DP_Lane_Count is (DP_Lane_Count_1, DP_Lane_Count_2, DP_Lane_Count_4);
    subtype DP_Lane_Count_Type is Pos64 range 1 .. 4;