purism/librem_skl: add libgfxinit support

Panel settings taken from KBL FSP sample vbt.bin

Test: build/boot librem13v2/15v3 with libgfxinit init,
verify both LFB and text modes functional

Change-Id: I9582065603417e53704244e95dde51a59f709664
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36123
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/mainboard/purism/librem_skl/Kconfig b/src/mainboard/purism/librem_skl/Kconfig
index a998a93..a58ca0b 100644
--- a/src/mainboard/purism/librem_skl/Kconfig
+++ b/src/mainboard/purism/librem_skl/Kconfig
@@ -8,6 +8,7 @@
 	select SOC_INTEL_COMMON_BLOCK_HDA_VERB
 	select SOC_INTEL_SKYLAKE
 	select SPD_READ_BY_WORD
+	select MAINBOARD_HAS_LIBGFXINIT
 	select MAINBOARD_HAS_LPC_TPM
 
 if BOARD_PURISM_BASEBOARD_LIBREM_SKL