cb/kabylake: don't hardcode power_on_after_fail

I realised that the Dell OptiPlex 3050 Micro has NVRAM available.
Use that backend, and hardcode power_on_after_fail to Disable,
which is already done in cmos.default.

The Lenovo ThinkPad T480 currently has no option table in coreboot,
besides the CBFS one. For this, the CBFS option table has been
enabled, and the build system has been modified to insert
a relevant config for power_on_after_fail.

Nicholas Chin informs me that Kabylake generally has legacy NVRAM,
so enabling it for the T480/T480s should work, but we'll need
to use it in the future anyway; better to just use CBFS now.

I *could* use the CBFS backend on 3050micro as well.

Signed-off-by: Leah Rowe <leah@libreboot.org>

config/coreboot/default/patches/0029-dell-3050micro-disable-nvme-hotplug.patch

@@ -1,7 +1,7 @@
-From 4ac77dd7d5c5759c546266003f7e705aae04860b Mon Sep 17 00:00:00 2001
+From 17c67799604e0e29192415e97293d71deb457cb2 Mon Sep 17 00:00:00 2001
 From: Leah Rowe <info@minifree.org>
 Date: Wed, 11 Dec 2024 01:06:01 +0000
-Subject: [PATCH 29/35] dell/3050micro: disable nvme hotplug
+Subject: [PATCH 29/40] dell/3050micro: disable nvme hotplug
 
 in my testing, when running my 3050micro for a few days,
 the nvme would sometimes randomly rename.
@@ -45,5 +45,5 @@ index 0d2adff74a..829acacab3 100644
  
  		# Realtek LAN
 -- 
-2.39.5
+2.47.3