[CIFS] Fix warnings shown by newer version of sparse

Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 4830acc..db5287a 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -397,7 +397,7 @@
 				/* BB Do not bother to decode buf since no
 				   local inode yet to put timestamps in,
 				   but we can reuse it safely */
-				int bytes_written;
+				unsigned int bytes_written;
 				struct win_dev *pdev;
 				pdev = (struct win_dev *)buf;
 				if (S_ISCHR(mode)) {