purism/librem_bdw: add/use VBT file

Add VBT file extracted from vendor (AMI) firmware,
use by default to ensure functional display after
resume from S3 when using libgfxinit.

Test: build/boot Librem 13v1/15v2 boards, verify
functional display after resume from S3 when using libgfxinit.

Signed-off-by: Matt DeVillier <matt.devillier@puri.sm>
Change-Id: I44d75486da3083cd1f07ea82dc18688db84a621e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36916
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/purism/librem_bdw/Kconfig

@@ -5,6 +5,7 @@ config BOARD_PURISM_BASEBOARD_LIBREM_BDW
 	select EC_PURISM_LIBREM
 	select HAVE_ACPI_RESUME
 	select HAVE_ACPI_TABLES
+	select INTEL_GMA_HAVE_VBT
 	select INTEL_INT15
 	select MAINBOARD_HAS_LIBGFXINIT
 	select SOC_INTEL_BROADWELL
@@ -73,6 +74,11 @@ config VGA_BIOS_ID
 	default "8086,1616" if BOARD_PURISM_LIBREM13_V1
 	default "8086,162b" if BOARD_PURISM_LIBREM15_V2
 
+# Override the default variant behavior, since the data.vbt is the same
+# for both variants.
+config INTEL_GMA_VBT_FILE
+	default "src/mainboard/$(MAINBOARDDIR)/data.vbt"
+
 # This platform has limited means to display POST codes
 config NO_POST
 	default y