powerpc/t4240qds: Update RCW, defconfig and maintainer

1. board/freescale/t4qds/t4_rcw.cfg
1.8GHz support is requested as default frequency, so update the rcw.

2. remove un-used configs
configs/T4160QDS_SPIFLASH_defconfig
configs/T4240QDS_SPIFLASH_defconfig
SPI boot is not available on T4QDS, so the configs should be removed.

3. board/freescale/t4qds/MAINTAINERS
Updated MAINTAINERS accordingly.

Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
[York Sun: revise subject]
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/board/freescale/t4qds/MAINTAINERS b/board/freescale/t4qds/MAINTAINERS
index fd340f3..b159113 100644
--- a/board/freescale/t4qds/MAINTAINERS
+++ b/board/freescale/t4qds/MAINTAINERS
@@ -1,16 +1,14 @@
 T4QDS BOARD
-#M:	-
+M:	Shaohui Xie <Shaohui.Xie@freescale.com>
 S:	Maintained
 F:	board/freescale/t4qds/
 F:	include/configs/T4240QDS.h
 F:	configs/T4160QDS_defconfig
 F:	configs/T4160QDS_NAND_defconfig
 F:	configs/T4160QDS_SDCARD_defconfig
-F:	configs/T4160QDS_SPIFLASH_defconfig
 F:	configs/T4240QDS_defconfig
 F:	configs/T4240QDS_NAND_defconfig
 F:	configs/T4240QDS_SDCARD_defconfig
-F:	configs/T4240QDS_SPIFLASH_defconfig
 F:	configs/T4240QDS_SRIO_PCIE_BOOT_defconfig
 
 T4160QDS_SECURE_BOOT BOARD