MAINTAINERS: Rename BOOTDEVICE

Rename this to BOOTSTD which is the normal name for the feature.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 19ca57d..f995394 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -918,7 +918,7 @@
 F:	include/blkmap.h
 F:	test/dm/blkmap.c
 
-BOOTDEVICE
+BOOTSTD
 M:	Simon Glass <sjg@chromium.org>
 S:	Maintained
 F:	boot/bootdev*.c