drivers/intel/gma: Power up legacy VGA block early

This is required at least on Skylake to be able to configure text mode.
3rdparty/libgfxinit is also updated by the single commit:

    42fb2d065d gma: Add procedure to power up legacy VGA block

Change-Id: I2fe144765e2b2acd9f6b76db375cae5b8feb5489
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/21386
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

3rdparty/libgfxinit

@@ -1 +1 @@
-Subproject commit 3a0e2a08f5489f3bb5c6e9f97b903e6e10c31a6c
+Subproject commit 42fb2d065d604eb08c723ac6b96aeebb4c84cbd3

src/drivers/intel/gma/text_fb/gma.adb

@@ -47,6 +47,7 @@ is
             Max_Pipe => Primary);
 
          if configs (Primary).Port /= Disabled then
+            HW.GFX.GMA.Power_Up_VGA;
             vga_io_init;
             vga_textmode_init;