Convert CONFIG_SYS_DDR_RAW_TIMING to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_DDR_RAW_TIMING

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P2020RDB-PC_defconfig b/configs/P2020RDB-PC_defconfig
index e15213a..fef773c 100644
--- a/configs/P2020RDB-PC_defconfig
+++ b/configs/P2020RDB-PC_defconfig
@@ -52,6 +52,7 @@
 CONFIG_DDR_CLK_FREQ=66666666
 CONFIG_SYS_SPD_BUS_NUM=1
 CONFIG_CHIP_SELECTS_PER_CTRL=1
+CONFIG_SYS_DDR_RAW_TIMING=y
 CONFIG_SYS_BR0_PRELIM_BOOL=y
 CONFIG_SYS_BR0_PRELIM=0xEF001001
 CONFIG_SYS_OR0_PRELIM=0xFC000FF7