gma: Add Map_Linear_FB()

Change-Id: Ia8850256b3a679e3b76567a6e3146e4c3dc38960
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/20609
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/hw-gfx-gma.ads b/common/hw-gfx-gma.ads
index 5b66803..3771804 100644
--- a/common/hw-gfx-gma.ads
+++ b/common/hw-gfx-gma.ads
@@ -101,6 +101,10 @@
    with
       Pre => Is_Initialized and HW.Config.Dynamic_MMIO;
 
+   procedure Map_Linear_FB (Linear_FB : out Word64; FB : in Framebuffer_Type)
+   with
+      Pre => Is_Initialized and HW.Config.Dynamic_MMIO;
+
 private
 
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