fs: ext4 write: return file len on success

After rework of the file system API, the size of ext4
write was missed. This causes printing unreliable write
size at the end of the file system write operation.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>

fs/ext4/ext4_write.c

@@ -1000,10 +1000,13 @@ int ext4_write_file(const char *filename, void *buf, loff_t offset,
 	}
 	ext4fs_close();
 
+	*actwrite = len;
+
 	return 0;
 
 fail:
 	ext4fs_close();
+	*actwrite = 0;
 
 	return -1;
 }