Convert CONFIG_SPL_COMMON_INIT_DDR to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_COMMON_INIT_DDR

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P1010RDB-PB_NAND_defconfig b/configs/P1010RDB-PB_NAND_defconfig
index 42981c5..da189ce 100644
--- a/configs/P1010RDB-PB_NAND_defconfig
+++ b/configs/P1010RDB-PB_NAND_defconfig
@@ -68,6 +68,7 @@
 CONFIG_FSL_CAAM=y
 CONFIG_DDR_CLK_FREQ=66666666
 CONFIG_CHIP_SELECTS_PER_CTRL=1
+CONFIG_TPL_COMMON_INIT_DDR=y
 CONFIG_DM_I2C=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
 CONFIG_TPL_SYS_I2C_LEGACY=y