[inpaint pipeline] fix bug for multiple prompts inputs (apple#959)

Author: xiaohu2015

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion_inpaint.py

@@ -340,8 +340,8 @@ def __call__(
         masked_image_latents = 0.18215 * masked_image_latents
 
         # duplicate mask and masked_image_latents for each generation per prompt, using mps friendly method
-        mask = mask.repeat(num_images_per_prompt, 1, 1, 1)
-        masked_image_latents = masked_image_latents.repeat(num_images_per_prompt, 1, 1, 1)
+        mask = mask.repeat(batch_size * num_images_per_prompt, 1, 1, 1)
+        masked_image_latents = masked_image_latents.repeat(batch_size * num_images_per_prompt, 1, 1, 1)
 
         mask = torch.cat([mask] * 2) if do_classifier_free_guidance else mask
         masked_image_latents = (