Fixed UnboundLocalError

[ka1tte]

Fixed the UnboundLocalError in the sample_dpmpp_2m_sde and sample_dpmpp_3m_sde functions.

File "/workspace/stable-diffusion-webui/modules/processing.py", line 867, in process_images_inner
  samples_ddim = p.sample(conditioning=p.c, unconditional_conditioning=p.uc, seeds=p.seeds, subseeds=p.subseeds, subseed_strength=p.subseed_strength, prompts=p.prompts)
File "/workspace/stable-diffusion-webui/modules/processing.py", line 1528, in sample
  samples = self.sampler.sample_img2img(self, self.init_latent, x, conditioning, unconditional_conditioning, image_conditioning=self.image_conditioning)
File "/workspace/stable-diffusion-webui/modules/sd_samplers_kdiffusion.py", line 188, in sample_img2img
  samples = self.launch_sampling(t_enc + 1, lambda: self.func(self.model_wrap_cfg, xi, extra_args=self.sampler_extra_args, disable=False, callback=self.callback_state, **extra_params_kwargs))
File "/workspace/stable-diffusion-webui/modules/sd_samplers_common.py", line 261, in launch_sampling
  return func()
File "/workspace/stable-diffusion-webui/modules/sd_samplers_kdiffusion.py", line 188, in <lambda>
  samples = self.launch_sampling(t_enc + 1, lambda: self.func(self.model_wrap_cfg, xi, extra_args=self.sampler_extra_args, disable=False, callback=self.callback_state, **extra_params_kwargs))
File "/workspace/stable-diffusion-webui/venv/lib/python3.10/site-packages/torch/utils/_contextlib.py", line 115, in decorate_context
  return func(*args, **kwargs)
File "/workspace/stable-diffusion-webui/repositories/k-diffusion/k_diffusion/sampling.py", line 701, in sample_dpmpp_3m_sde
  h_1, h_2 = h, h_1
UnboundLocalError: local variable 'h' referenced before assignment

This seems to be a problem that has arisen previously. #74