board_f: Rename initdram() to dram_init()

This allows us to use the same DRAM init function on all archs. Add a
dummy function for arc, which does not use DRAM init here.

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Dummy function on nios2]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/freescale/t208xrdb/spl.c b/board/freescale/t208xrdb/spl.c
index a5f940c..b431401 100644
--- a/board/freescale/t208xrdb/spl.c
+++ b/board/freescale/t208xrdb/spl.c
@@ -98,7 +98,7 @@
 
 	i2c_init_all();
 
-	initdram();
+	dram_init();
 
 #ifdef CONFIG_SPL_MMC_BOOT
 	mmc_boot();