drivers: pci_ep: Introduce UCLASS_PCI_EP uclass

Introduce new UCLASS_PCI_EP class for handling PCI endpoint
devices, allowing to set various attributes of the PCI endpoint
device, such as:
* configuration space header
* BAR definitions
* outband memory mapping
* start/stop PCI link

Signed-off-by: Ramon Fried <ramon.fried@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci_endpoint/Kconfig b/drivers/pci_endpoint/Kconfig
new file mode 100644
index 0000000..ac4f43d
--- /dev/null
+++ b/drivers/pci_endpoint/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# PCI Endpoint Support
+#
+
+menu "PCI Endpoint"
+
+config PCI_ENDPOINT
+	bool "PCI Endpoint Support"
+	depends on DM
+	help
+	   Enable this configuration option to support configurable PCI
+	   endpoints. This should be enabled if the platform has a PCI
+	   controllers that can operate in endpoint mode (as a device
+	   connected to PCI host or bridge).
+
+endmenu