Following the benchmarking of GEOS-Chem 13.2.0 with the Luo et al. (2020)
wet deposition scheme, Gan Luo noticed a bug in the code. He wrote:

   Simulated sulfate mass concentration looks lower than what I expected.

   I checked https://github.com/geoschem/geos-chem/blob/13.2.0-beta.0/GeosCore/sulfate_mod.F90
   It seems that we missed some switches for Non-volatile aerosol
   concentration calculation:

   (1) At line 5142 D = (2.e+0_fp*SO4nss) - (TNA+2.e+0_fp*TDCA), it should be:

       #ifdef LUO_WETDEP
          D = (1.5e+0_fp*SO4nss) - (TNA+2.e+0_fp*TDCA)
       #else
          D = (2.e+0_fp*SO4nss) - (TNA+2.e+0_fp*TDCA)
       #endif

   (2) At line 5156 D = (2.e+0_fp * SO4nss) - TNA), it should be:

       #ifdef LUO_WETDEP
          D = (1.5e+0_fp * SO4nss) - TNA
       #else
          D = (2.e+0_fp * SO4nss) - TNA
       #endif

   Switching from 2.e+0_fp * SO4nss to 1.5e+0_fp * SO4nss is following the
   reasons introduced in Luo et al. (2020).

Signed-off-by: Melissa Sulprizio <mpayer@seas.harvard.edu>