3rdparty/libgfxinit: Update submodule pointer

Update libgfxinit to current master. Changes include:

* a fix to decode the size stolen memory correctly on pre-SandyBridge
  hardware,
* a PCI id based generation check, obsoleting the old check based
  on PCH audio ids,
* some minor improvements around rarely used DDI ports (D and E), and
* added support for tiled and rotated framebuffers on Skylake+ hardware
  (less interesting for coreboot, I guess?).

TEST=Booted kontron/ktqm77 (Ivy Bridge) and pending kontron/bsl6
     (Skylake) both with text and linear framebuffers and observed
     FILO's prompt showing up.

Change-Id: I9a3c35c60b9edf8775f3a489df7577092910e127
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/25453
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

3rdparty/libgfxinit

@@ -1 +1 @@
-Subproject commit 42fb2d065d604eb08c723ac6b96aeebb4c84cbd3
+Subproject commit 7628493a7e7acaba93d607db008a59ec8fa8eebe

src/drivers/intel/gma/hires_fb/gma.adb

@@ -83,6 +83,7 @@ is
             fb.Width    := Width_Type (min_h);
             fb.Height   := Height_Type (min_v);
             fb.Stride   := Div_Round_Up (fb.Width, 16) * 16;
+            fb.V_Stride := fb.Height;
 
             for i in Pipe_Index loop
                exit when configs (i).Port = Disabled;