fix unbroadcast

Author: MikeInnes

src/cuda/cudnn.jl

@@ -328,7 +328,7 @@ end
     h_ = hBatch(x, data(h))
     dx, dh = backwardData(descs[m], y, dy, dho, h_, reserve)
     (dWi, dWh), db = backwardWeights(descs[m], data(x), h_, y, reserve)
-    nobacksies(:RNN, (dx, unbroadcast(size(h), dh), transpose(dWi), transpose(dWh), db))
+    nobacksies(:RNN, (dx, unbroadcast(h, dh), transpose(dWi), transpose(dWh), db))
   end
 end
 
@@ -342,7 +342,7 @@ end
     dx, dh, dc = backwardData(descs[m], y, dy, dho, dco, h_, c_, reserve)
     (dWi, dWh), db = backwardWeights(descs[m], data(x), h_, y, reserve)
     nobacksies(:RNN,
-      (dx, unbroadcast(size(h), dh), unbroadcast(size(c), dc),
+      (dx, unbroadcast(h, dh), unbroadcast(c, dc),
        transpose(dWi), transpose(dWh), db))
   end
 end