[telemac3d] Fix deleting useless check of ZPLANE for planes 1 and NPLAN

(bottom and free surface planes) with mesh transformation = 3 (fixed z)
Check introduced in MR !233

sources/telemac3d/condim.f

@@ -252,7 +252,7 @@
           CALL PLANTE(1)
         ENDIF
       ENDDO
-      DO I=1,NPLAN-1
+      DO I=2,NPLAN-2
         IF((TRANSF_PLANE%I(I).EQ.3.AND.TRANSF_PLANE%I(I+1).EQ.3)
      &  .AND.ZPLANE%R(I+1).LE.ZPLANE%R(I)) THEN
           WRITE(LU,*) 'Z COORDINATE (ZPLANE) DOES NOT INCREASE ',