Merge branch 'kaizhangpnl/atm/ieflx_cleanup' (PR #1498)

Further modifications to check_energy.F90

Further modifications to check_energy.F90 to address the need from the
coupled team. Cleaned up the IEFLX code and added more comments.
Please note that the namelist variable l_ieflx_fix was removed and the
fixer can be switched on if ieflx_opt is 1 or 2 (recommended value is
2).

The problem associated with #1479 went away with those changes.

SHFLXFIX was removed. Instead, we output SHFLXORI (SHFLX before
applying the IEFLX fixer).

IEFLX is now a constant field (global mean IEFLX) and default output.

Also removed the pbuf variable for IEFLX, since it is not used at this
time.

[BFB] for prognostic fields, but IEFLX and SHFLXFIX are changed/removed.

Fixes #1479

* kaizhangpnl/atm/ieflx_cleanup:
  Further modifications to check_energy.F90 to address the need from the coupled team.
  minor comment
  Bugfix for the IEFLX fixer

Conflicts:
	components/cam/src/physics/cam/phys_control.F90