[Libomptarget] Remove duplicate data environment exit

Summary:
This patch removes a duplicated exit from the OpenMP data envrionment.
We already have an RAII method that guards this environment so it is
unnecessary.

Author: jhuber6

openmp/libomptarget/DeviceRTL/src/Parallelism.cpp

@@ -90,7 +90,6 @@ void __kmpc_parallel_51(IdentTy *ident, int32_t, int32_t if_expr,
     state::DateEnvironmentRAII DERAII(ident);
     ++icv::Level;
     invokeMicrotask(TId, 0, fn, args, nargs);
-    state::exitDataEnvironment();
     return;
   }