Discrepancy in handling of crop seed deficit in summary variables for C vs. N

### Brief summary of bug

This is a minor bug that I think just impacts some diagnostic fields: I noticed that there is a difference between C and N in the handling of crop seed deficit in the calculation of summary variables: For N, cropseedn_deficit_patch is added to storvegn_patch (and thus also contributes to totvegn_patch), but this is not the case for C (for cropseedc_deficit_patch).

I'm not sure which is desired: the C or N handling.

### General bug information

**CTSM version you are using:** latest master

**Does this bug cause significantly incorrect results in the model's science?** Probably not – just results in small issues in diagnostic fields.

**Configurations affected:** all with crop

@danicalombardozzi any thoughts on which is correct?