typo in CNP timing of update fine-root mass

[rgknox]

Describe the issue

There is a typo in this line:
https://github.com/NGEET/fates/blob/main/parteh/PRTAllometricCNPMod.F90#L1911

Should be:

limiting_n = ((n_uptake_mode .eq. coupled_n_uptake) .and. (hlm_nitrogen_suppl .eq. ifalse))

Not:

limiting_n = ((n_uptake_mode .eq. coupled_p_uptake) .and. (hlm_nitrogen_suppl .eq. ifalse))

The good: It is unlikely this will affect many CNP users. This is because when coupling is turned on, it is typical to have BOTH coupled_n_uptake and coupled_p_uptake set to true. We regulate N and P limitation through supplementation on the ELM side of the code.

This is an important fix though as we bring in N coupling with CTSM.

cc @slevis-lmwg