All messages that use the dev_err function slows down booting and make it look ugly. 
Change Invalid PCI ROM header signature message to use the dev_info function in ./drivers/pci/rom.c

All computers with a Amd gpu do have this message and works fine, so there is no errors.
size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size)
{
	void __iomem *image;
	int last_image;
	unsigned length;

	image = rom;
	do {
		void __iomem *pds;
		/* Standard PCI ROMs start out with these bytes 55 AA */
		if (readw(image) != 0xAA55) {
			dev_info(&pdev->dev, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n",
				readw(image));
			break;
		}