imx: boards: Add maintainers info

Add MAINTAINERS info for mx6slevk_spl, mx6ul_9x9_evk and mx6qpsabreauto.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>

board/freescale/mx6qsabreauto/MAINTAINERS

 MX6QSABREAUTO BOARD
 M:	Fabio Estevam <fabio.estevam@freescale.com>
+M:	Peng Fan <Peng.Fan@freescale.com>
 S:	Maintained
 F:	board/freescale/mx6qsabreauto/
 F:	include/configs/mx6qsabreauto.h
 F:	configs/mx6dlsabreauto_defconfig
 F:	configs/mx6qsabreauto_defconfig
+F:	configs/mx6qpsabreauto_defconfig

board/freescale/mx6slevk/MAINTAINERS

 MX6SLEVK BOARD
 M:	Fabio Estevam <fabio.estevam@freescale.com>
+M:	Peng Fan <Peng.Fan@freescale.com>
 S:	Maintained
 F:	board/freescale/mx6slevk/
 F:	include/configs/mx6slevk.h
 F:	configs/mx6slevk_defconfig
+F:	configs/mx6slevk_spl_defconfig
 F:	configs/mx6slevk_spinor_defconfig

board/freescale/mx6ul_14x14_evk/MAINTAINERS

@@ -4,3 +4,4 @@ S:	Maintained
 F:	board/freescale/mx6ul_14x14_evk/
 F:	include/configs/mx6ul_14x14_evk.h
 F:	configs/mx6ul_14x14_evk_defconfig
+F:	configs/mx6ul_9x9_evk_defconfig