pci: Add Apple PCIe controller driver

This driver supports the PCIe controller on the Apple M1 and
M2 SoCs.  The code is adapted from the Linux driver.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index a3b662f..ef328d2 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -105,6 +105,15 @@
 	  Note that this must be configured when boot because Linux driver
 	  expects the PCIe RC has been configured in the bootloader.
 
+config PCIE_APPLE
+	bool "Enable Apple PCIe driver"
+	depends on ARCH_APPLE
+	imply PCI_INIT_R
+	default y
+	help
+	  Say Y here if you want to enable PCIe controller support on
+	  Apple SoCs.
+
 config PCI_GT64120
 	bool "GT64120 PCI support"
 	depends on MIPS