fix handling of flash_attention

Author: danielenricocahall

keras/src/backend/openvino/nn.py

@@ -698,7 +698,7 @@ def dot_product_attention(
             "`dot_product_attention` with `bias` is not supported "
             "with openvino backend"
         )
-    if flash_attention is not None:
+    if flash_attention:
         raise NotImplementedError(
             "`dot_product_attention` with `flash_attention` is not supported "
             "with openvino backend"

keras/src/ops/nn_test.py

@@ -2458,7 +2458,7 @@ def test_dot_product_attention(
             )
 
         if flash_attention:
-            if backend.backend() in ("tensorflow", "numpy"):
+            if backend.backend() in ("tensorflow", "numpy", "openvino"):
                 self.skipTest(
                     "Flash attention is not supported in tensorflow and numpy "
                     "backends."