warp7: MAINTAINERS: Add an entry for warp7_bl33_defconfig

Add an entry for the warp7_bl33_defconfig target.

This fixes the following warnings:

WARNING: no status info for 'warp7_bl33'
WARNING: no maintainers for 'warp7_bl33'

Reported-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
diff --git a/board/warp7/MAINTAINERS b/board/warp7/MAINTAINERS
index 1d3ee29..55f8c81 100644
--- a/board/warp7/MAINTAINERS
+++ b/board/warp7/MAINTAINERS
@@ -4,3 +4,4 @@
 F:	board/warp7/
 F:	include/configs/warp7.h
 F:	configs/warp7_defconfig
+F:	configs/warp7_bl33_defconfig