[Offload] Remove unused field IsBareKernel. (llvm#139815)

Author: dhruvachak

offload/plugins-nextgen/common/include/PluginInterface.h

@@ -389,9 +389,6 @@ struct GenericKernelTy {
 
   /// The prototype kernel launch environment.
   KernelLaunchEnvironmentTy KernelLaunchEnvironment;
-
-  /// If the kernel is a bare kernel.
-  bool IsBareKernel = false;
 };
 
 /// Information about an allocation, when it has been allocated, and when/if it