mb/system76/rpl: Add Gazelle 18

The Gazelle 18 (gaze18) is a Raptor Lake-H board.

Tested with a custom TianoCore UefiPayloadPkg.

Working:

- PS/2 keyboard
- I2C HID touchpad
- Both DIMM slots
- M.2 NVMe SSD slot
- M.2 SATA SSD slot
- All USB ports
- Webcam
- Ethernet
- WiFi/Bluetooth
- Integrated graphics using Intel GOP driver
- Internal microphone
- Internal speakers
- Combined headphone + mic 3.5mm audio
- 3.5mm microphone input
- S3 suspend/resume
- Booting Pop!_OS Linux 22.04 with kernel 6.2.6

Not working:

- Discrete/Hybrid graphics

Change-Id: I4599bf12c0f3048f9328f336cc8971400f5fd1a0
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73395
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Jeremy Soller <jeremy@system76.com>

Documentation/mainboard/system76/gaze18.md

@@ -0,0 +1,72 @@
+# System76 Gazelle 18 (gaze18)
+
+## Specs
+
+- CPU
+  - Intel i9-13900H
+- Chipset
+  - Intel HM770
+- EC
+  - ITE IT5570E running [System76 EC](https://github.com/system76/ec)
+- Graphics
+  - NVIDIA GeForce RTX 3050 (70W TDP)
+  - Intel Irix Xe Graphics
+  - eDP displays
+    - 17.3" 1920x1080@144Hz LCD
+    - 15.6" 1920x1080@144Hz LCD
+  - External outputs
+    - 1x HDMI 2.1
+    - 1x Mini DisplayPort 1.4
+- Memory
+  - Up to 64GB (2x32GB) dual-channel DDR4 SO-DIMMs @ 3200 MHz
+- Networking
+  - Realtek RTL8111H gigabit Ethernet
+  - M.2 PCIe/CNVi WiFi/Bluetooth
+    - Intel Wi-Fi 6E AX210/AX211
+- Power
+  - 150W AC barrel adapter
+    - Included: LiteOn PA-1151-76, using a C5 power cord
+  - 54Wh 4-cell battery (NP50BAT-4-54)
+- Sound
+  - Realtek ALC256 codec
+  - Internal speakers and microphone
+  - Combined 3.5mm headphone/microphone jack
+  - Dedicated 3.5mm microphone jack
+  - HDMI, mDP audio
+- Storage
+  - 1x M.2 (PCIe NVMe Gen 4)
+  - 1x M.2 (PCIe NVMe Gen 3)
+  - MicroSD card reader
+    - Realtek RTS5227S
+- USB
+  - 2x USB 3.2 Gen 2 Type-C
+    - Does not support USB-C charging (USB-PD) or Thunderbolt
+  - 1x USB 3.2 Gen 2 Type-A
+  - 1x USB 2.0 Type-A
+- Dimensions
+  - 15": 35.95cm x 23.8cm x 2.27cm, 1.99kg
+  - 17": 39.69cm x 26.2cm x 2.5cm, 2.41kg
+
+## Flashing coreboot
+
+```eval_rst
++---------------------+---------------------+
+| Type                | Value               |
++=====================+=====================+
+| Socketed flash      | no                  |
++---------------------+---------------------+
+| Vendor              | GigaDevice          |
++---------------------+---------------------+
+| Model               | GD25B256E           |
++---------------------+---------------------+
+| Size                | 32 MiB              |
++---------------------+---------------------+
+| Package             | WSON-8              |
++---------------------+---------------------+
+| Internal flashing   | yes                 |
++---------------------+---------------------+
+| External flashing   | yes                 |
++---------------------+---------------------+
+```
+
+The flash chip (U24) is right of the M.2 SSD connectors.