Philippe 30/11/2021: SURFEX: fix: initialise CPARAMBVOC of namelist NAM_CH_ISBAN

(cherry picked from commit 37ea99b9)

src/SURFEX/modn_isban.F90

@@ -108,7 +108,7 @@ LOGICAL  :: LSNOWDRIFT_SUBLIM
 LOGICAL  :: LSNOW_ABS_ZENITH
  CHARACTER(3) :: CSNOWMETAMO
  CHARACTER(3) :: CSNOWRAD
- CHARACTER(LEN=6)  :: CCH_DRY_DEP, CPARAMBVOC
+ CHARACTER(LEN=6)  :: CCH_DRY_DEP, CPARAMBVOC=''
  CHARACTER(LEN=28) :: CCHEM_SURF_FILE
 !
 NAMELIST/NAM_ISBAn/CC1DRY,CSCOND,CSOILFRZ,CDIFSFCOND,CSNOWRES,CCPSURF, &