use_fates_sp and use_fates_ed_st3 are allowed to be on at the same time

[ekluzek]

Describe the issue

I was able to turn SP mode and ST3 mode on at the same time. This apparently should not be allowed, per @adrifoster and @glemieux.

I'll add a check to CTSM for this in the namelist build. But, we probably should have checking in the FATES Fortran code as well. And there might be other control variable checking that would be good to have in place as well.

Relevant log output

FATES tag

sci.1.81.0_api.37.1.0

Host land model tag

ctsm5.3.030

Machine

derecho

Other supported machine name

No response

Additional context

No response