drop layer support_image_storage and option use_image_storage (#6126)

* fix pyncnn build

python/tests/benchmark.py

@@ -148,7 +148,6 @@ if __name__ == "__main__":
     opt.use_int8_arithmetic = True
     opt.use_packing_layout = True
     opt.use_shader_pack8 = False
-    opt.use_image_storage = False
 
     ncnn.set_cpu_powersave(powersave)
     ncnn.set_omp_dynamic(0)

python/tests/test_option.py

@@ -113,11 +113,6 @@ def test_option():
     opt.use_subgroup_ops = False
     assert opt.use_subgroup_ops == False
 
-    opt.use_image_storage = True
-    assert opt.use_image_storage == True
-    opt.use_image_storage = False
-    assert opt.use_image_storage == False
-
     opt.use_tensor_storage = True
     assert opt.use_tensor_storage == True
     opt.use_tensor_storage = False