video: simplefb: Fix build warn with CONFIG_FDT_64BIT=n

Fix compile warning with !CONFIG_FDT_64BIT by
casting the variable in the debug print.

Signed-off-by: Eva Kurchatova <lekkit@at.encryp.ch>
Reported-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/drivers/video/simplefb.c b/drivers/video/simplefb.c
index cb518b1..239b006 100644
--- a/drivers/video/simplefb.c
+++ b/drivers/video/simplefb.c
@@ -27,7 +27,8 @@
 		return -EINVAL;
 	}
 
-	debug("%s: base=%llx, size=%llu\n", __func__, base, size);
+	debug("%s: base=%llx, size=%llu\n",
+	      __func__, (unsigned long long)base, (unsigned long long)size);
 
 	/*
 	 * TODO is there some way to reserve the framebuffer