gma: Move transcoder setup into own package

Split the transcoder setup out of `Pipe_Setup` into a new package
`Transcoder`. This comes closer to how Intel's manuals describe the
hardware.

Also rework the related constant definitions to make things more
human readable.

Change-Id: Ife0f0d635d87b874d4b713a00ca7a1bec688c672
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/17764
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index 00a46e1..b3492f4 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -40,7 +40,7 @@
    Disable_Trickle_Feed    : constant Boolean := not
                                                 (CPU in Haswell .. Broadwell);
    Pipe_Enabled_Workaround : constant Boolean := CPU = Broadwell;
-   Has_EDP_Pipe            : constant Boolean := CPU >= Haswell;
+   Has_EDP_Transcoder      : constant Boolean := CPU >= Haswell;
    Has_Pipe_DDI_Func       : constant Boolean := CPU >= Haswell;
    Has_Trans_Clk_Sel       : constant Boolean := CPU >= Haswell;
    Has_Pipe_MSA_Misc       : constant Boolean := CPU >= Haswell;