Remove IPD (step 1) (NCAR#215)

Remove all IPD source files that are not needed to compile with CCPP. Update gfsphysics/CMakeLists.txt and gfsphysics/GFS_layer/GFS_driver.F90 so that the code compiles after removing IPD sources.

Also: update submodule pointer for GFDL_atmos_cubed_sphere to include PR NOAA-EMC/GFDL_atmos_cubed_sphere#48 ("Removed use of mpp_node for use with FMS 2020.04").

Author: climbfuji

atmos_cubed_sphere

@@ -12,15 +12,10 @@ if(32BIT)
 endif()
 
 set(CCPP_SOURCES
-    physics/mersenne_twister.f
     physics/namelist_soilveg.f
     physics/set_soilveg.f
-
     physics/noahmp_tables.f90
 
-    physics/GFDL_parse_tracers.F90
-    physics/physcons.F90
-
     CCPP_layer/CCPP_data.F90
     ${CMAKE_BINARY_DIR}/FV3/ccpp/physics/ccpp_static_api.F90