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/keymile/km83xx/km83xx.c b/board/keymile/km83xx/km83xx.c
index f83fa06..8020c37 100644
--- a/board/keymile/km83xx/km83xx.c
+++ b/board/keymile/km83xx/km83xx.c
@@ -330,7 +330,7 @@
 	return msize;
 }
 
-int initdram(void)
+int dram_init(void)
 {
 	immap_t *im = (immap_t *)CONFIG_SYS_IMMR;
 	u32 msize = 0;