MdePkg/IndustryStandard: Remove an incorrectly spelled macro

MdePkg/IndustryStandard: Remove an incorrectly spelled macro

EFI_RETURNING_FROM_EFI_APPLICATOIN is not correctly spelled,
so now remove it.
https://bugzilla.tianocore.org/show_bug.cgi?id=1368

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>