gma skl: Add I_boost configuration

Hardcoded to 1 since we don't support Skylake-Y (ULX).

Change-Id: I22fa056531cac18828c867f9c9f5745ec424d38c
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/20168
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index ec41c40..f40054c 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -95,6 +95,7 @@
    Has_DDI_Buffer_Trans    : constant Boolean := CPU >= Haswell and
                                                  CPU /= Broxton;
    Has_Low_Voltage_Swing   : constant Boolean := CPU >= Broxton;
+   Has_Iboost_Config       : constant Boolean := CPU >= Skylake;
 
    Need_DP_Aux_Mutex       : constant Boolean := False; -- Skylake & (PSR | GTC)