Fix MLP.jittable() bug in case return_emb=True

[rusty1s]

No description provided.

[codecov]

Codecov Report

Merging #4645 (57dfa70) into master (cfaea95) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4645   +/-   ##
=======================================
  Coverage   82.93%   82.93%           
=======================================
  Files         316      316           
  Lines       16750    16750           
=======================================
  Hits        13891    13891           
  Misses       2859     2859           

Impacted Files	Coverage Δ
torch_geometric/nn/models/mlp.py	98.46% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cfaea95...57dfa70. Read the comment docs.