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>

arch/xtensa/cpu/cpu.c

@@ -47,3 +47,8 @@ int arch_cpu_init(void)
 	gd->ram_size = CONFIG_SYS_SDRAM_SIZE;
 	return 0;
 }
+
+int dram_init(void)
+{
+	return 0;
+}