Thomp nc density fix submodule pointer rrtmgp

[climbfuji]

This is what I did:

git clone -b thomp_nc_density --recursive https://github.com/tanyasmirnova/ccpp-physics ccpp-physics-thomp_nc_density
cd ccpp-physics-thomp_nc_density/physics/rte-rrtmgp/
git remote update
git checkout 33c8a984c17cf41be5d4c2928242e1b4239bfc40
cd ../..
git status
git add physics/rte-rrtmgp
git commit -m "Update submodule pointer for physics/rte-rrtmgp"
git checkout -b thomp_nc_density
git push dom thomp_nc_density

After you merge this PR into your ccpp-physics branch and check it out locally, you will need to run

git submodule update

inside FV3/ccpp/physics and it should say something like checked out rte-rrrtmgp 33c8a984c17cf41be5d4c2928242e1b4239bfc40. And git status should not show any changes to rte-rrtmgp.