A quick patch to make Mochi VAE works on macOS

comfyui_mochi_vae_on_mps.diff

diff --git a/comfy/ldm/genmo/vae/model.py b/comfy/ldm/genmo/vae/model.py
index b68d48a..694b33a 100644
--- a/comfy/ldm/genmo/vae/model.py
+++ b/comfy/ldm/genmo/vae/model.py
@@ -78,7 +78,12 @@ class PConv3d(ops.Conv3d):
         # Apply padding.
         assert self.padding_mode == "replicate"  # DEBUG
         mode = "constant" if self.padding_mode == "zeros" else self.padding_mode
+        is_mps_device = x.device.type == "mps"
+        if is_mps_device:
+            x = x.to("cpu")
         x = F.pad(x, (0, 0, 0, 0, pad_front, pad_back), mode=mode)
+        if is_mps_device:
+            x = x.to("mps")
         return super().forward(x)