powerpc/defconfig: Rename defconfig file for T1040QDS/T1024QDS DDR4 targets

Previously the DDR4 targets were named with _D4. Rename them with
_DDR4 for easy identification.

Signed-off-by: York Sun <yorksun@freescale.com>

board/freescale/t102xqds/MAINTAINERS

@@ -7,6 +7,6 @@ F:	configs/T1024QDS_defconfig
 F:	configs/T1024QDS_NAND_defconfig
 F:	configs/T1024QDS_SDCARD_defconfig
 F:	configs/T1024QDS_SPIFLASH_defconfig
-F:	configs/T1024QDS_D4_defconfig
+F:	configs/T1024QDS_DDR4_defconfig
 F:	configs/T1024QDS_SECURE_BOOT_defconfig
-F:	configs/T1024QDS_D4_SECURE_BOOT_defconfig
+F:	configs/T1024QDS_DDR4_SECURE_BOOT_defconfig

board/freescale/t1040qds/MAINTAINERS

@@ -4,7 +4,7 @@ S:	Maintained
 F:	board/freescale/t1040qds/
 F:	include/configs/T1040QDS.h
 F:	configs/T1040QDS_defconfig
-F:	configs/T1040QDS_D4_defconfig
+F:	configs/T1040QDS_DDR4_defconfig
 
 T1040QDS_SECURE_BOOT BOARD
 M:	Aneesh Bansal <aneesh.bansal@freescale.com>