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/arch/powerpc/cpu/ppc4xx/spl_boot.c b/arch/powerpc/cpu/ppc4xx/spl_boot.c
index f3aa46c..b30f169 100644
--- a/arch/powerpc/cpu/ppc4xx/spl_boot.c
+++ b/arch/powerpc/cpu/ppc4xx/spl_boot.c
@@ -26,7 +26,7 @@
 	 * First we need to initialize the SDRAM, so that the real
 	 * U-Boot or the OS (Linux) can be loaded
 	 */
-	initdram();
+	dram_init();
 
 	/* Clear bss */
 	memset(__bss_start, '\0', __bss_end - __bss_start);