nxp: Migrate a number of DDR related symbols to Kconfig

- Guard most of the options in drivers/ddr/fsl/Kconfig with
  SYS_FSL_DDR || SYS_FSL_MMDC.
- Migrate FSL_DMA, DDR_ECC, DDR_ECC_CMD, and ECC_INIT_VIA_DDRCONTROLLER
  to Kconfig.
- Clean up the logic for including the DDR_ECC_CMD code.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/MPC8349EMDS_SDRAM_defconfig b/configs/MPC8349EMDS_SDRAM_defconfig
index 9a8dac3..74a5bcd 100644
--- a/configs/MPC8349EMDS_SDRAM_defconfig
+++ b/configs/MPC8349EMDS_SDRAM_defconfig
@@ -108,6 +108,8 @@
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_ENV_ADDR=0xFE080000
 CONFIG_ENV_ADDR_REDUND=0xFE0A0000
+CONFIG_DDR_ECC=y
+CONFIG_ECC_INIT_VIA_DDRCONTROLLER=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_FSL=y
 CONFIG_SYS_FSL_I2C_OFFSET=0x3000