Fix typo in absolute_pos_embed dimension check (C1 != C1 -> C1 != C2)

[Mr-Neutr0n]

Summary

• Fixed a typo in utils.py load_pretrained() where the dimension mismatch check for absolute_pos_embed compares C1 != C1 (always False) instead of the intended C1 != C2.
• This means that when loading pretrained weights with a different embedding channel dimension, the guard clause never triggers. Instead of a clear warning message, users get a confusing runtime error downstream.
• The analogous check for relative_position_bias_table correctly uses nH1 != nH2, confirming this is a typo.

Test plan

• Verified the one-character fix (C1 -> C2) matches the pattern used elsewhere in the same function
• No functional change for the common case where dimensions match (the else branch executes either way)
• For the mismatch case: previously would error out in interpolate; now correctly logs a warning and skips