Add missing polygon types to SoilHydrologyMod

Not all polygon types were being imported from
landunit_varcon, commit adds the missing polygon types.

components/elm/src/biogeophys/SoilHydrologyMod.F90

@@ -272,7 +272,7 @@ subroutine Infiltration(bounds, num_hydrologyc, filter_hydrologyc, num_urbanc, f
      use elm_varcon       , only : denh2o, denice, roverg, wimp, mu, tfrz
      use elm_varcon       , only : pondmx, watmin
      use column_varcon    , only : icol_roof, icol_road_imperv, icol_sunwall, icol_shadewall, icol_road_perv
-     use landunit_varcon  , only : istsoil, istcrop, ilowcenpoly
+     use landunit_varcon  , only : istsoil, istcrop, ilowcenpoly, iflatcenpoly, ihighcenpoly
      use elm_time_manager , only : get_step_size, get_nstep
      use atm2lndType      , only : atm2lnd_type ! land river two way coupling
      use lnd2atmType      , only : lnd2atm_type