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/ifm/ac14xx/ac14xx.c b/board/ifm/ac14xx/ac14xx.c
index 129eb47..3486137 100644
--- a/board/ifm/ac14xx/ac14xx.c
+++ b/board/ifm/ac14xx/ac14xx.c
@@ -310,7 +310,7 @@
 	/* EMPTY, optional, we don't do it */
 };
 
-int initdram(void)
+int dram_init(void)
 {
 	gd->ram_size = fixed_sdram(NULL, sdram_init_seq,
 				   ARRAY_SIZE(sdram_init_seq));