imx:mx6sxsabresd board spl support

Add board level spl support for mx6sxsabresd board.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
diff --git a/board/freescale/mx6sxsabresd/MAINTAINERS b/board/freescale/mx6sxsabresd/MAINTAINERS
index f52f300..c0f5d9c 100644
--- a/board/freescale/mx6sxsabresd/MAINTAINERS
+++ b/board/freescale/mx6sxsabresd/MAINTAINERS
@@ -4,3 +4,4 @@
 F:	board/freescale/mx6sxsabresd/
 F:	include/configs/mx6sxsabresd.h
 F:	configs/mx6sxsabresd_defconfig
+F:	configs/mx6sxsabresd_spl_defconfig