fix typos in Registry_noahmp for acc output variables in restart file

[CharlesZheZhang]

This PR is to fix a few typos in the Registry_noahmp.xml file.
Essentially it is for outputing a few accumulated water fluxes per soil timestep in the restart file
correcting typo, for example, from acc_ecan to acc_ecanxy, for the correct variable name.

[cenlinhe]

This bug fix looks good to me. It does not affect model run by default because MPAS uses the same main timestep as Noah-MP soil timestep.

[mgduda]

@CharlesZheZhang @cenlinhe With the changes in this PR, I'm seeing the following compilation error:

ERROR: Field acc_ssoilxy is not unique.
ERROR: Structures and Fields are required to have unique names for I/O reasons.
       Please fix duplicates in the Registry.xml file.
       You may use the name_in_code attribute to give them the same name inside the model,
       but the name attribute is required to be unique.

Looking through the Registry_noahmp.xml file, it does appear that there is already an entry for acc_ssoilxy before the changes in this PR rename acc_ssoil to acc_ssoilxy.

[cenlinhe]

@mgduda a quick question: it seems that the existing "acc_ssoilxy" is in the "output_noahmp" structure part while the one fixed in this PR is in the "diag_physics_noahmp" structure, both in the sf_noahmp_in package. So what is the difference between "diag_physics_noahmp" and "output_noahmp"? Variables cannot share the same name in these two different structures? Originally, I thought "diag_physics_noahmp" variables are for restart file while "output_noahmp" are for model output files, but it seems my understanding is wrong?