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/arch/powerpc/cpu/mpc83xx/Makefile b/arch/powerpc/cpu/mpc83xx/Makefile
index aeb42b1..7c4ef76 100644
--- a/arch/powerpc/cpu/mpc83xx/Makefile
+++ b/arch/powerpc/cpu/mpc83xx/Makefile
@@ -26,7 +26,7 @@
 obj-y += cpu_init.o
 obj-y += speed.o
 obj-y += interrupts.o
-obj-y += ecc.o
+obj-$(CONFIG_DDR_ECC_CMD) += ecc.o
 ifndef CONFIG_PINCTRL
 obj-$(CONFIG_QE) += qe_io.o
 endif