avr32: Fix printf() format warnings

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/board/atmel/atstk1000/atstk1000.c b/board/atmel/atstk1000/atstk1000.c
index 6371e2d..d284fc1 100644
--- a/board/atmel/atstk1000/atstk1000.c
+++ b/board/atmel/atstk1000/atstk1000.c
@@ -104,7 +104,7 @@
 	unmap_physmem(sdram_base, EBI_SDRAM_SIZE);
 
 	if (expected_size != actual_size)
-		printf("Warning: Only %u of %u MiB SDRAM is working\n",
+		printf("Warning: Only %lu of %lu MiB SDRAM is working\n",
 				actual_size >> 20, expected_size >> 20);
 
 	return actual_size;