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/Makefile b/drivers/Makefile
index 6635dab..603aa98 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -86,6 +86,7 @@
 obj-y += misc/
 obj-$(CONFIG_MMC) += mmc/
 obj-$(CONFIG_NVME) += nvme/
+obj-$(CONFIG_PCI_ENDPOINT) += pci_endpoint/
 obj-y += pcmcia/
 obj-y += dfu/
 obj-$(CONFIG_PCH) += pch/