arm: mvebu: Move SoC selection (A38X vs AXP) into Kconfig

Until now, the SoC selection for the ARCH_MVEBU platforms has been done
in the config header. Using CONFIG_ARMADA_XP in a non-clear way. As
it needed to get selected for AXP and A38x based boards. This patch
now changes this to move the SoC selection to Kconfig. And also
uses CONFIG_ARCH_MVEBU as a common define for both AXP and A38x.
This makes things a bit clearer - especially for new board additions.

Additionally the defines CONFIG_SYS_MVEBU_DDR_AXP and
CONFIG_SYS_MVEBU_DDR_A38X are replaced with the already available
CONFIG_ARMADA_38X and CONFIG_ARMADA_XP.

And CONFIG_DDR3 is removed, as its not referenced anywhere.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>
diff --git a/arch/arm/mach-mvebu/Makefile b/arch/arm/mach-mvebu/Makefile
index 21c56a4..b96b81b 100644
--- a/arch/arm/mach-mvebu/Makefile
+++ b/arch/arm/mach-mvebu/Makefile
@@ -15,8 +15,8 @@
 obj-y	= cpu.o
 obj-y	+= dram.o
 ifndef CONFIG_SPL_BUILD
-obj-$(CONFIG_SYS_MVEBU_DDR_A38X) += ../../../drivers/ddr/marvell/a38x/xor.o
-obj-$(CONFIG_SYS_MVEBU_DDR_AXP) += ../../../drivers/ddr/marvell/axp/xor.o
+obj-$(CONFIG_ARMADA_38X) += ../../../drivers/ddr/marvell/a38x/xor.o
+obj-$(CONFIG_ARMADA_XP) += ../../../drivers/ddr/marvell/axp/xor.o
 endif
 obj-y	+= gpio.o
 obj-y	+= mbus.o
@@ -24,7 +24,7 @@
 obj-$(CONFIG_SPL_BUILD) += spl.o
 obj-$(CONFIG_SPL_BUILD) += lowlevel_spl.o
 
-obj-$(CONFIG_SYS_MVEBU_DDR_A38X) += serdes/a38x/
-obj-$(CONFIG_SYS_MVEBU_DDR_AXP)	+= serdes/axp/
+obj-$(CONFIG_ARMADA_38X) += serdes/a38x/
+obj-$(CONFIG_ARMADA_XP) += serdes/axp/
 
 endif