mx6: add mmdc configuration for MX6Q/MX6DL

- add function for configuring iomux based on board-specific regs
- add function for configuring mmdc based on board-specific and
  chip-specific data

Cc: Stefan Roese <sr@denx.de>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Andy Ng <andreas2025@gmail.com>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Cc: Tapani Utriainen <tapani@technexion.com>
Cc: Tom Rini <trini@ti.com>

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
diff --git a/arch/arm/cpu/armv7/mx6/Makefile b/arch/arm/cpu/armv7/mx6/Makefile
index d7285fc..6dc9f8e 100644
--- a/arch/arm/cpu/armv7/mx6/Makefile
+++ b/arch/arm/cpu/armv7/mx6/Makefile
@@ -8,4 +8,5 @@
 #
 
 obj-y	:= soc.o clock.o
+obj-$(CONFIG_SPL_BUILD)	     += ddr.o
 obj-$(CONFIG_SECURE_BOOT)    += hab.o