pci_ep: add pci endpoint sandbox driver

Add a dummy PCI endpoint for sandbox.
Supporting only a single function, it allows setting
and reading header configuration.

Signed-off-by: Ramon Fried <ramon.fried@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/Kconfig b/arch/Kconfig
index 28afe39..355d214 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -90,6 +90,7 @@
 	select DM_SPI_FLASH
 	select HAVE_BLOCK_DEVICE
 	select LZO
+	select PCI_ENDPOINT
 	select SPI
 	select SUPPORT_OF_CONTROL
 	imply BITREVERSE
@@ -120,6 +121,7 @@
 	imply VIRTIO_BLK
 	imply VIRTIO_NET
 	imply DM_SOUND
+	imply PCI_SANDBOX_EP
 	imply PCH
 
 config SH