Have temporary ability to set lfrac mapping for mizuRoute from mapconsd to mapconsf

[ekluzek]

The need for this should go away if #408 is done. But, as that is likely a more longer term project in the short term, I need a way to bypass the mapconsd mapping for lfrac for the ROF grid. I think adding a simple namelist control item to do this in med_map_mod.F90 would work. When #408 is done, these changes would be removed.

This is due to this issue in mizuRoute

ESCOMP/mizuRoute#426

[billsacks]

From discussion with @mvertens - she suggests just changing the lnd -> rof mappings in esmFldsExchange_cesm_mod.F90 from mapconsf to mapconsd (and ideally doing the verification to confirm that this doesn't change answers by much). For mizuRoute this shouldn't change answers at all (since you're using an existing mapping file); for other configurations, the answer changes are expected to be (very) small.

@mvertens would significantly prefer this over adding a namelist control.