CIFS: Fix build failure with smb2

I saw the following build error during a randconfig build:

fs/cifs/smb2ops.c: In function 'smb2_new_lease_key':
fs/cifs/smb2ops.c:1104:2: error: implicit declaration of function 'generate_random_uuid' [-Werror=implicit-function-declaration]

Explicit include the right header to fix this issue.
Signed-off-by: Tobias Regnery <tobias.regnery@gmail.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/smb2ops.c

@@ -21,6 +21,7 @@
 #include <linux/vfs.h>
 #include <linux/falloc.h>
 #include <linux/scatterlist.h>
+#include <linux/uuid.h>
 #include <crypto/aead.h>
 #include "cifsglob.h"
 #include "smb2pdu.h"