Please use coder.loadDeepLearningNetwork instead of coder.load in your MATLAB file.
If you dont have a GPU, you can still generate a MEX file from this if you have MATLAB coder , and the deep learning support package for MATLAB Coderhttps://www.mathworks.com/matlabcentral/fileexchange/68612-matlab-coder-interface-for-deep-learning-libraries
See an example here