arm: imx: mx53loco: remove usage of mx53_dram_size

Static variables are not available during board_init_f().
'static uint32_t mx53_dram_size[2];' was used in board specific
dram_init(), dram_init_banksize() and get_effective_memsize() to avoid
multiple calls to get_ram_size().

Reused dram initialization functions from arch/arm/mach-imx/mx5/mx53_dram.c

Signed-off-by: Patrick Bruenn <p.bruenn@beckhoff.com>
diff --git a/arch/arm/mach-imx/mx5/Makefile b/arch/arm/mach-imx/mx5/Makefile
index 2cc2cbc..4e305e9 100644
--- a/arch/arm/mach-imx/mx5/Makefile
+++ b/arch/arm/mach-imx/mx5/Makefile
@@ -13,3 +13,4 @@
 # common files for mx53 dram initialization
 obj-$(CONFIG_TARGET_M53EVK)     += mx53_dram.o
 obj-$(CONFIG_TARGET_MX53CX9020) += mx53_dram.o
+obj-$(CONFIG_TARGET_MX53LOCO)   += mx53_dram.o