No activation within CamEncoder MLP

Hi,

Great work!

When looking into the codebase, we notice there is no activation between two MLP in CamEncoder https://github.com/lucifer443/RecurrentBEV/blob/main/bev/models/middle_encoders/depth_encoders.py#L92

Could you illustrate a bit the rational behind it? 

Thanks