drivers/gfx/nvidia: Add driver for NVIDIA GPU

Add a driver for laptops with NVIDIA Optimus (hybrid) graphics. The
driver provides ACPI support for dynamically powering on and off the
GPU, NVIDIA Dynamic Boost support, and a function for enabling the GPU
power in romstage.

References:
- DG-09845-001: NVIDIA GN20/QN20 Hardware Design Guide
- DG-09954-001: NVIDIA GN20/QN20 Software Design Guide

Change-Id: I2dec7aa2c8db7994f78a7cc1220502676e248465
Signed-off-by: Jeremy Soller <jeremy@system76.com>
Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/drivers/gfx/nvidia/chip.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _DRIVERS_GFX_NVIDIA_CHIP_H_
+#define _DRIVERS_GFX_NVIDIA_CHIP_H_
+
+struct drivers_gfx_nvidia_config {
+	/* TODO: Set GPIOs in devicetree? */
+};
+
+#endif /* _DRIVERS_GFX_NVIDIA_CHIP_H_ */