Add Dell OptiPlex 3040 Micro support

Adds libreboot support for the Dell OptiPlex 3040 Micro based on the
OptiPlex 3050 Micro (same Skylake H110 PCH-H platform). Key differences:
DDR3L SODIMMs, Pentium G4400T-class CPUs (Skylake only), Realtek ALC3234
HDA, and Boot Guard neutralization via deguard.

Tested and booted on hardware.

Signed-off-by: Todd Baker <todd_baker@student.uml.edu>

config/coreboot/dell3040micro_vfsp_16mb/target.cfg

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+tree="default"
+xarch="i386-elf"
+payload_seabios="y"
+payload_grub="y"
+payload_memtest="y"
+grub_scan_disk="nvme ahci"
+grubtree="xhci_nvme"
+vcfg="3040micro"
+build_depend="seabios/default grub/xhci_nvme memtest86plus u-boot/amd64coreboot"
+IFD_platform="sklkbl"
+payload_uboot="amd64"