AVR32: Use initdram() instead of board_init_memories()

Conform to the "standard" interface and use initdram() instead of
board_init_memories() on AVR32. This enables us to get rid of the
sdram_size member of the global_data struct as well.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/board/atmel/atstk1000/atstk1000.c b/board/atmel/atstk1000/atstk1000.c
index 8210bc6..9f735da 100644
--- a/board/atmel/atstk1000/atstk1000.c
+++ b/board/atmel/atstk1000/atstk1000.c
@@ -53,9 +53,9 @@
 	return 0;
 }
 
-void board_init_memories(void)
+long int initdram(int board_type)
 {
-	gd->sdram_size = sdram_init(&sdram);
+	return sdram_init(&sdram);
 }
 
 void board_init_info(void)