bootstd: ethernet: Add a bootdev driver

Add a bootdev driver for Ethernet. It can use the PXE boot mechanism to
locate a file, added later.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 239fa2e..77a3408 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -707,6 +707,7 @@
 F:	include/bootflow.h
 F:	include/bootmeth.h
 F:	include/bootstd.h
+F:	net/eth_bootdevice.c
 
 BTRFS
 M:	Marek Behun <marek.behun@nic.cz>