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>

board/freescale/t4qds/MAINTAINERS

 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

board/freescale/t4qds/t4_rcw.cfg

 #PBL preamble and RCW header
 aa55aa55 010e0100
 #serdes protocol  1_27_5_11
-16070019 18101916 00000000 00000000
+1607001b 18101b16 00000000 00000000
 04362858 30548c00 ec020000 f5000000
 00000000 ee0000ee 00000000 000307fc
 00000000 00000000 00000000 00000028

configs/T4160QDS_SPIFLASH_defconfig

-CONFIG_SYS_EXTRA_OPTIONS="PPC_T4160,RAMBOOT_PBL,SPIFLASH,SYS_TEXT_BASE=0xFFF40000"
-CONFIG_PPC=y
-CONFIG_MPC85xx=y
-CONFIG_TARGET_T4240QDS=y

configs/T4240QDS_SPIFLASH_defconfig

-CONFIG_SYS_EXTRA_OPTIONS="PPC_T4240,RAMBOOT_PBL,SPIFLASH,SYS_TEXT_BASE=0xFFF40000"
-CONFIG_PPC=y
-CONFIG_MPC85xx=y
-CONFIG_TARGET_T4240QDS=y