gma pipe_setup: Add registers for second plane

We want to use the secondary plane to allow a preprocessed cursor,
for rotation for instance.

Change-Id: Ib3fc2a5636dddf2541e7bf2ce9c243575eb353d3
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.sourcearcade.org/c/libgfxinit/+/542
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Thomas Heijligen <src@posteo.de>
diff --git a/common/hw-gfx-gma-pipe_setup.adb b/common/hw-gfx-gma-pipe_setup.adb
index 7b79fc4..b045233 100644
--- a/common/hw-gfx-gma-pipe_setup.adb
+++ b/common/hw-gfx-gma-pipe_setup.adb
@@ -997,7 +997,7 @@
       if CUR.FBC_CTL /= Registers.Invalid_Register then
          Registers.Write (CUR.FBC_CTL, 16#0000_0000#);
       end if;
-      Registers.Unset_Mask (Controller.SPCNTR, DSPCNTR_ENABLE);
+      Registers.Unset_Mask (Controller.PLANE_2_CTL, DSPCNTR_ENABLE);
       if Config.Has_Plane_Control then
          Clear_Watermarks (Controller);
          Registers.Unset_Mask (Controller.PLANE_CTL, PLANE_CTL_PLANE_ENABLE);