Fix fromStreamD performance

Before: not finishing in reasonable time
After: 686 us (similar to fromStream)

benchmark/Streamly/Benchmark/Data/Unfold.hs

@@ -590,7 +590,7 @@ o_1_space_generation size =
           "generation"
           [ benchIO "fromStream" $ fromStream size
           , benchIO "fromStreamK" $ fromStreamK size
-          , benchIO "fromStreamD (n/100)" $ fromStreamD (size `div` 100)
+          , benchIO "fromStreamD" $ fromStreamD size
           -- Very small benchmarks, reporting in ns
           -- , benchIO "nilM" $ nilM size
           , benchIO "consM" $ consM size

src/Streamly/Internal/Data/Unfold.hs

@@ -351,7 +351,7 @@ fromStreamD = Unfold step return
     where
 
     {-# INLINE_LATE step #-}
-    step (Stream step1 state1) = do
+    step (UnStream step1 state1) = do
         r <- step1 defState state1
         return $ case r of
             Yield x s -> Yield x (Stream step1 s)