[L] Change in coreboot[main]: mb/lattepanda: Add support for LattePanda Mu

[KunYi Chen (Code Review)]

Attention is currently required from: KunYi Chen.

Hello Nicholas Chin, build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/83719?usp=email

to look at the new patch set (#5).

The following approvals got outdated and were removed:
Verified+1 by build bot (Jenkins)

Change subject: mb/lattepanda: Add support for LattePanda Mu
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mb/lattepanda: Add support for LattePanda Mu

Add initial support for the LattePanda Mu board, which features:
  Intel Alder Lake-N N100 processor
  8GB LPDDR5 memory
  64GB eMMC storage
  SO-DIMM 260-pin connector for function expansion

This commit includes:
  Basic board configuration
  Memory initialization
  Essential I/O setup

Testing with Lite carrier board
  Booting into default installed Windows: Passed
  USB 3.0/2.0: Working
  HDMI output: Working
  Realtek Ethernet: Working

S3 sleep mode: Failed
  Power on after shutdown: Failed (requires power removal)
  Installing Ubuntu 22.04: Failed (system shuts down, unable to auto-reboot)
  UART of SuperIO in OS: Missing
  Environment Controller: Not supported
  M.2/M Key: Not working (booting failed with SSD 512GB installed)

Change-Id: I79696bdd837a221860b32f54629212c3346dca66
Signed-off-by: KunYi Chen 
---
A configs/config.lattepanda_mu
A src/mainboard/lattepanda/Kconfig
A src/mainboard/lattepanda/Kconfig.name
A src/mainboard/lattepanda/mu/Kconfig
A src/mainboard/lattepanda/mu/Kconfig.name
A src/mainboard/lattepanda/mu/Makefile.mk
A src/mainboard/lattepanda/mu/board_info.txt
A src/mainboard/lattepanda/mu/bootblock.c
A src/mainboard/lattepanda/mu/data.vbt
A src/mainboard/lattepanda/mu/devicetree.cb
A src/mainboard/lattepanda/mu/dsdt.asl
A src/mainboard/lattepanda/mu/gpio.c
A src/mainboard/lattepanda/mu/include/baseboard/gpio.h
A src/mainboard/lattepanda/mu/include/baseboard/variants.h
A src/mainboard/lattepanda/mu/mainboard.c
A src/mainboard/lattepanda/mu/memory.c
A src/mainboard/lattepanda/mu/ramstage.c
A src/mainboard/lattepanda/mu/romstage_fsp_params.c
A src/mainboard/lattepanda/mu/spd/Makefile.mk
A src/mainboard/lattepanda/mu/spd/empty.spd.hex
A src/mainboard/lattepanda/mu/spd/mu_lp5_16gb.spd.hex
A src/mainboard/lattepanda/mu/spd/mu_lp5_8gb.spd.hex
22 files changed, 763 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/19/83719/5