ppc: Rename MPC8XXX_INIT_DDR_SUPPORT to MPC8XXX_INIT_DDR

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/ls1043ardb_sdcard_defconfig b/configs/ls1043ardb_sdcard_defconfig
index 9078000..a625ec7 100644
--- a/configs/ls1043ardb_sdcard_defconfig
+++ b/configs/ls1043ardb_sdcard_defconfig
@@ -36,7 +36,7 @@
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0xf0
 CONFIG_SPL_ENV_SUPPORT=y
-CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT=y
+CONFIG_SPL_MPC8XXX_INIT_DDR=y
 CONFIG_SPL_WATCHDOG=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_SPL=y