mo_read_forcing_nc.f90 does not support reading monthly climatology of LAI

Consistency checks for meteorologic files does not allow to read-in climatologic LAI values using mo_read_forcing_nc.f90 (monthly values have time dimension of 12). I will investigate this issue later on, for time being be aware ... @ottor @shresthap @rkumar @thober @lese

We need to have a check case for reading LAI climatology "timeStep_LAI_input = -2"