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/MAINTAINERS b/MAINTAINERS
index bea3122..e916841 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -633,6 +633,12 @@
 S:	Maintained
 F:	tools/patman/
 
+PCI Endpoint
+M:	Ramon Fried <rfried.dev@gmail.com>
+S:	Maintained
+F:	drivers/pci_endpoint/
+F:  include/pci_ep.h
+
 POWER
 M:	Jaehoon Chung <jh80.chung@samsung.com>
 S:	Maintained